1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
|
<html>
<head>
<title>RecurrentJS Sentence Memorization Demo</title>
<meta http-equiv='Content-Type' content='text/html; charset=utf-8' />
<style>
body {
font-family: Arial, "Helvetica Neue", Helvetica, sans-serif;
color: #333;
padding: 20px;
}
#argmax {
background-color: #DFD;
}
#ppl {
color: #090;
font-size: 20px;
}
#epoch {
color: #900;
font-size: 20px;
}
.apred {
padding: 2px;
margin: 5px;
overflow: hidden;
height: 20px;
font-size: 14px;
}
#prepro_status {
background-color: #FFD;
padding: 5px;
}
#status {
padding: 2px;
margin-top: 5px;
}
#controls {
margin: 5px;
}
.theslider {
width:90%;
display: inline-block;
}
.slider_value {
width: 9%;
display: inline-block;
}
#wrap {
width: 800px;
margin-right: auto;
margin-left: auto;
margin-bottom: 200px;
}
.abutton {
width: 120px;
height: 30px;
margin: 10px 10px 10px 0px;
}
.hh {
background-color: #EEE;
padding: 5px;
margin-top: 5px;
border-bottom: 1px solid #999;
margin-bottom: 2px;
}
#pplgraph {
float: right;
}
#intro {
text-align: justify;
}
</style>
<link href="external/jquery-ui.min.css" rel="stylesheet">
<script src="external/jquery-1.8.3.min.js"></script>
<script src="external/jquery-ui.min.js"></script>
<script src="src/recurrent.js"></script>
<script src="src/vis.js"></script>
<script type="text/javascript">
// prediction params
var sample_softmax_temperature = 1.0; // how peaky model predictions should be
var max_chars_gen = 100; // max length of generated sentences
// various global var inits
var epoch_size = -1;
var input_size = -1;
var output_size = -1;
var letterToIndex = {};
var indexToLetter = {};
var vocab = [];
var data_sents = [];
var solver = new R.Solver(); // should be class because it needs memory for step caches
var pplGraph = new Rvis.Graph();
var model = {};
var initVocab = function(sents, count_threshold) {
// go over all characters and keep track of all unique ones seen
var txt = sents.join(''); // concat all
// count up all characters
var d = {};
for(var i=0,n=txt.length;i<n;i++) {
var txti = txt[i];
if(txti in d) { d[txti] += 1; }
else { d[txti] = 1; }
}
// filter by count threshold and create pointers
letterToIndex = {};
indexToLetter = {};
vocab = [];
// NOTE: start at one because we will have START and END tokens!
// that is, START token will be index 0 in model letter vectors
// and END token will be index 0 in the next character softmax
var q = 1;
for(ch in d) {
if(d.hasOwnProperty(ch)) {
if(d[ch] >= count_threshold) {
// add character to vocab
letterToIndex[ch] = q;
indexToLetter[q] = ch;
vocab.push(ch);
q++;
}
}
}
// globals written: indexToLetter, letterToIndex, vocab (list), and:
input_size = vocab.length + 1;
output_size = vocab.length + 1;
epoch_size = sents.length;
$("#prepro_status").text('found ' + vocab.length + ' distinct characters: ' + vocab.join(''));
}
var utilAddToModel = function(modelto, modelfrom) {
for(var k in modelfrom) {
if(modelfrom.hasOwnProperty(k)) {
// copy over the pointer but change the key to use the append
modelto[k] = modelfrom[k];
}
}
}
var initModel = function() {
// letter embedding vectors
var model = {};
model['Wil'] = new R.RandMat(input_size, letter_size , 0, 0.08);
if(generator === 'rnn') {
var rnn = R.initRNN(letter_size, hidden_sizes, output_size);
utilAddToModel(model, rnn);
} else {
var lstm = R.initLSTM(letter_size, hidden_sizes, output_size);
utilAddToModel(model, lstm);
}
return model;
}
var reinit_learning_rate_slider = function() {
// init learning rate slider for controlling the decay
// note that learning_rate is a global variable
$("#lr_slider").slider({
min: Math.log10(0.01) - 3.0,
max: Math.log10(0.01) + 0.05,
step: 0.05,
value: Math.log10(learning_rate),
slide: function( event, ui ) {
learning_rate = Math.pow(10, ui.value);
$("#lr_text").text(learning_rate.toFixed(5));
}
});
$("#lr_text").text(learning_rate.toFixed(5));
}
var reinit = function() {
// note: reinit writes global vars
// eval options to set some globals
eval($("#newnet").val());
reinit_learning_rate_slider();
solver = new R.Solver(); // reinit solver
pplGraph = new Rvis.Graph();
ppl_list = [];
tick_iter = 0;
// process the input, filter out blanks
var data_sents_raw = $('#ti').val().split('\n');
data_sents = [];
for(var i=0;i<data_sents_raw.length;i++) {
var sent = data_sents_raw[i].trim();
if(sent.length > 0) {
data_sents.push(sent);
}
}
initVocab(data_sents, 1); // takes count threshold for characters
model = initModel();
}
var saveModel = function() {
var out = {};
out['hidden_sizes'] = hidden_sizes;
out['generator'] = generator;
out['letter_size'] = letter_size;
var model_out = {};
for(var k in model) {
if(model.hasOwnProperty(k)) {
model_out[k] = model[k].toJSON();
}
}
out['model'] = model_out;
var solver_out = {};
solver_out['decay_rate'] = solver.decay_rate;
solver_out['smooth_eps'] = solver.smooth_eps;
step_cache_out = {};
for(var k in solver.step_cache) {
if(solver.step_cache.hasOwnProperty(k)) {
step_cache_out[k] = solver.step_cache[k].toJSON();
}
}
solver_out['step_cache'] = step_cache_out;
out['solver'] = solver_out;
out['letterToIndex'] = letterToIndex;
out['indexToLetter'] = indexToLetter;
out['vocab'] = vocab;
$("#tio").val(JSON.stringify(out));
}
var loadModel = function(j) {
hidden_sizes = j.hidden_sizes;
generator = j.generator;
letter_size = j.letter_size;
model = {};
for(var k in j.model) {
if(j.model.hasOwnProperty(k)) {
var matjson = j.model[k];
model[k] = new R.Mat(1,1);
model[k].fromJSON(matjson);
}
}
solver = new R.Solver(); // have to reinit the solver since model changed
solver.decay_rate = j.solver.decay_rate;
solver.smooth_eps = j.solver.smooth_eps;
solver.step_cache = {};
for(var k in j.solver.step_cache){
if(j.solver.step_cache.hasOwnProperty(k)){
var matjson = j.solver.step_cache[k];
solver.step_cache[k] = new R.Mat(1,1);
solver.step_cache[k].fromJSON(matjson);
}
}
letterToIndex = j['letterToIndex'];
indexToLetter = j['indexToLetter'];
vocab = j['vocab'];
// reinit these
ppl_list = [];
tick_iter = 0;
}
var forwardIndex = function(G, model, ix, prev) {
var x = G.rowPluck(model['Wil'], ix);
// forward prop the sequence learner
if(generator === 'rnn') {
var out_struct = R.forwardRNN(G, model, hidden_sizes, x, prev);
} else {
var out_struct = R.forwardLSTM(G, model, hidden_sizes, x, prev);
}
return out_struct;
}
var predictSentence = function(model, samplei, temperature) {
if(typeof samplei === 'undefined') { samplei = false; }
if(typeof temperature === 'undefined') { temperature = 1.0; }
var G = new R.Graph(false);
var s = '';
var prev = {};
while(true) {
// RNN tick
var ix = s.length === 0 ? 0 : letterToIndex[s[s.length-1]];
var lh = forwardIndex(G, model, ix, prev);
prev = lh;
// sample predicted letter
logprobs = lh.o;
if(temperature !== 1.0 && samplei) {
// scale log probabilities by temperature and renormalize
// if temperature is high, logprobs will go towards zero
// and the softmax outputs will be more diffuse. if temperature is
// very low, the softmax outputs will be more peaky
for(var q=0,nq=logprobs.w.length;q<nq;q++) {
logprobs.w[q] /= temperature;
}
}
probs = R.softmax(logprobs);
if(samplei) {
var ix = R.samplei(probs.w);
} else {
var ix = R.maxi(probs.w);
}
if(ix === 0) break; // END token predicted, break out
if(s.length > max_chars_gen) { break; } // something is wrong
var letter = indexToLetter[ix];
s += letter;
}
return s;
}
var costfun = function(model, sent) {
// takes a model and a sentence and
// calculates the loss. Also returns the Graph
// object which can be used to do backprop
var n = sent.length;
var G = new R.Graph();
var log2ppl = 0.0;
var cost = 0.0;
var prev = {};
for(var i=-1;i<n;i++) {
// start and end tokens are zeros
var ix_source = i === -1 ? 0 : letterToIndex[sent[i]]; // first step: start with START token
var ix_target = i === n-1 ? 0 : letterToIndex[sent[i+1]]; // last step: end with END token
lh = forwardIndex(G, model, ix_source, prev);
prev = lh;
// set gradients into logprobabilities
logprobs = lh.o; // interpret output as logprobs
probs = R.softmax(logprobs); // compute the softmax probabilities
log2ppl += -Math.log2(probs.w[ix_target]); // accumulate base 2 log prob and do smoothing
cost += -Math.log(probs.w[ix_target]);
// write gradients into log probabilities
logprobs.dw = probs.w;
logprobs.dw[ix_target] -= 1
}
var ppl = Math.pow(2, log2ppl / (n - 1));
return {'G':G, 'ppl':ppl, 'cost':cost};
}
function median(values) {
values.sort( function(a,b) {return a - b;} );
var half = Math.floor(values.length/2);
if(values.length % 2) return values[half];
else return (values[half-1] + values[half]) / 2.0;
}
var ppl_list = [];
var tick_iter = 0;
var tick = function() {
// sample sentence fromd data
var sentix = R.randi(0,data_sents.length);
var sent = data_sents[sentix];
var t0 = +new Date(); // log start timestamp
// evaluate cost function on a sentence
var cost_struct = costfun(model, sent);
// use built up graph to compute backprop (set .dw fields in mats)
cost_struct.G.backward();
// perform param update
var solver_stats = solver.step(model, learning_rate, regc, clipval);
//$("#gradclip").text('grad clipped ratio: ' + solver_stats.ratio_clipped)
var t1 = +new Date();
var tick_time = t1 - t0;
ppl_list.push(cost_struct.ppl); // keep track of perplexity
// evaluate now and then
tick_iter += 1;
if(tick_iter % 50 === 0) {
// draw samples
$('#samples').html('');
for(var q=0;q<5;q++) {
var pred = predictSentence(model, true, sample_softmax_temperature);
var pred_div = '<div class="apred">'+pred+'</div>'
$('#samples').append(pred_div);
}
}
if(tick_iter % 10 === 0) {
// draw argmax prediction
$('#argmax').html('');
var pred = predictSentence(model, false);
var pred_div = '<div class="apred">'+pred+'</div>'
$('#argmax').append(pred_div);
// keep track of perplexity
$('#epoch').text('epoch: ' + (tick_iter/epoch_size).toFixed(2));
$('#ppl').text('perplexity: ' + cost_struct.ppl.toFixed(2));
$('#ticktime').text('forw/bwd time per example: ' + tick_time.toFixed(1) + 'ms');
if(tick_iter % 100 === 0) {
var median_ppl = median(ppl_list);
ppl_list = [];
pplGraph.add(tick_iter, median_ppl);
pplGraph.drawSelf(document.getElementById("pplgraph"));
}
}
}
var gradCheck = function() {
var model = initModel();
var sent = '^test sentence$';
var cost_struct = costfun(model, sent);
cost_struct.G.backward();
var eps = 0.000001;
for(var k in model) {
if(model.hasOwnProperty(k)) {
var m = model[k]; // mat ref
for(var i=0,n=m.w.length;i<n;i++) {
oldval = m.w[i];
m.w[i] = oldval + eps;
var c0 = costfun(model, sent);
m.w[i] = oldval - eps;
var c1 = costfun(model, sent);
m.w[i] = oldval;
var gnum = (c0.cost - c1.cost)/(2 * eps);
var ganal = m.dw[i];
var relerr = (gnum - ganal)/(Math.abs(gnum) + Math.abs(ganal));
if(relerr > 1e-1) {
console.log(k + ': numeric: ' + gnum + ', analytic: ' + ganal + ', err: ' + relerr);
}
}
}
}
}
var iid = null;
$(function() {
// attach button handlers
$('#learn').click(function(){
reinit();
if(iid !== null) { clearInterval(iid); }
iid = setInterval(tick, 0);
});
$('#stop').click(function(){
if(iid !== null) { clearInterval(iid); }
iid = null;
});
$("#resume").click(function(){
if(iid === null) {
iid = setInterval(tick, 0);
}
});
$("#savemodel").click(saveModel);
$("#loadmodel").click(function(){
var j = JSON.parse($("#tio").val());
loadModel(j);
});
$("#loadpretrained").click(function(){
$.getJSON("lstm_100_model.json", function(data) {
pplGraph = new Rvis.Graph();
learning_rate = 0.0001;
reinit_learning_rate_slider();
loadModel(data);
});
});
$("#learn").click(); // simulate click on startup
//$('#gradcheck').click(gradCheck);
$("#temperature_slider").slider({
min: -1,
max: 1.05,
step: 0.05,
value: 0,
slide: function( event, ui ) {
sample_softmax_temperature = Math.pow(10, ui.value);
$("#temperature_text").text( sample_softmax_temperature.toFixed(2) );
}
});
});
</script>
</head>
<body>
<a href="https://github.com/karpathy/recurrentjs"><img style="position: absolute; top: 0; right: 0; border: 0;" src="https://s3.amazonaws.com/github/ribbons/forkme_right_darkblue_121621.png" alt="Fork me on GitHub"></a>
<div id="wrap">
<h1>Deep Recurrent Nets character generation demo</h1>
<div id="intro">
This demo shows usage of the <a href="https://github.com/karpathy/recurrentjs">recurrentjs library</a> that allows you to train deep Recurrent Neural Networks (RNN) and Long Short-Term Memory Networks (LSTM) in Javascript. But the core of the library is more general and allows you to set up arbitrary expression graphs that support fully automatic backpropagation.<br><br>
In this demo we take a dataset of sentences as input and learn to memorize the sentences character by character. That is, the RNN/LSTM takes a character, its context from previous time steps (as mediated by the hidden layers) and predicts the next character in the sequence. Here is an example: <br><br>
<div style="text-align:center;"><img src="eg.png"></div>
In the example image above that depicts a deep RNN, every character has an associated "letter vector" that we will train with backpropagation. These letter vectors are combined through a (learnable) Matrix-vector multiply transformation into the first hidden layer representation (yellow), then into second hidden layer representation (purple), and finally into the output space (blue). The output space has dimensionality equal to the number of characters in the dataset and every dimension provides the probability of the next character in the sequence. The network is therefore trained to always predict the next character (using Softmax + cross-entropy loss on all letters). The quantity we track during training is called the <b>perplexity</b>, which measures how surprised the network is to see the next character in a sequence. For example, if perplexity is 4.0 then it's as if the network was guessing uniformly at random from 4 possible characters for next letter (i.e. lowest it can be is 1). At test time, the prediction is currently done iteratively character by character in a greedy fashion, but I might eventually implemented more sophisticated methods (e.g. beam search).<br><br>
The demo is pre-filled with sentences from <a href="http://www.paulgraham.com/articles.html">Paul Graham's essays</a>, in an attempt to encode Paul Graham's knowledge into the weights of the Recurrent Networks. The long-term goal of the project then is to generate startup wisdom at will. Feel free to train on whatever data you wish, and to experiment with the parameters. If you want more impressive models you have to increase the sizes of hidden layers, and maybe slightly the letter vectors. However, this will take longer to train.<br><br>
For suggestions/bugs ping me at <a href="https://twitter.com/karpathy">@karpathy</a>.<br><br>
</div>
<div>
<div class="hh">Input sentences:</div>
<textarea style="width:100%; height:200px;" id="ti">
the company has, say, 6 months of runway
or to put it more brutally, 6 months before they're out of business
they expect to avoid that by raising more from investors
that last sentence is the fatal one
it's hard to convince investors the first time too, but founders expect that
what bites them the second time is a confluence of three forces:
the company is spending more now than it did the first time it raised money
investors have much higher standards for companies that have already raised money
the company is now starting to read as a failure
the first time it raised money, it was neither a success nor a failure; it was too early to ask
i'm going to call the situation i described in the first paragraph "the fatal pinch
one of the things that makes the fatal pinch so dangerous is that it's self-reinforcing
y combinator tells founders who raise money to act as if it's the last they'll ever get
i will now, by an amazing feat of clairvoyance, do this for you: the probability is zero
you should shut down the company if you're certain it will fail no matter what you do
companies rarely have to fail though
what i'm really doing here is giving you the option of admitting you've already given up
if you don't want to shut down the company, that leaves increasing revenues and decreasing expenses
in most startups, expenses people and decreasing expenses firing people
if so, now's the time
which leaves two options, firing good people and making more money
you should lean more toward firing people if the source of your trouble is overhiring
plus those 15 people might not even be the ones you need for whatever you end up building
so the solution may be to shrink and then figure out what direction to grow in
it may seem facile to suggest a startup make more money, as if that could be done for the asking
usually a startup is already trying as hard as it can to sell whatever it sells
but only work on whatever will get you the most revenue the soonest
or you may have expertise in some new field they don't understand
and to the extent you can, try to avoid the worst pitfalls of consulting
you keep the ip and no billing by the hour
you just have to realize in time that you're near death
and if you're in the fatal pinch, you are
it struck me recently how few of the most successful people i know are mean
there are exceptions, but remarkably few
meanness isn't rare
in fact, one of the things the internet has shown us is how mean people can be
a few decades ago, only famous people and professional writers got to publish their opinions
now everyone can, and we can all see the long tail of meanness that had previously been hidden
what's going on here? are meanness and success inversely correlated?
part of what's going on, of course, is selection bias
i only know people who work in certain fields: startup founders, programmers, professors
i'm willing to believe that successful people in other fields are mean
maybe successful hedge fund managers are mean; i don't know enough to say
it seems quite likely that most successful drug lords are mean
being married to her is like standing next to an airport baggage scanner
why? i think there are several reasons
one is that being mean makes you stupid
that's why i hate fights
you never do your best work in a fight, because fights are not sufficiently general
winning is always a function of the situation and the people involved
and yet fighting is just as much work as thinking about real problems
startups don't win by attacking
they win by transcending
there are exceptions of course, but usually the way to win is to race ahead, not to stop and fight
another reason mean founders lose is that they can't get the best people to work for them
they can hire people who will put up with them because they need a job
but the best people have other options
a mean person can't convince the best people to work for him unless he is super convincing
and while having the best people helps any organization, it's critical for startups
the startup founders who end up richest are not the ones driven by money
[1] the ones who keep going are driven by something else
they may not say so explicitly, but they're usually trying to improve the world
which means people with a desire to improve the world have a natural advantage
this kind of work is the future
for most of history success meant control of scarce resources
for most of history, success meant success at zero-sum games
and in most of them meanness was not a handicap but probably an advantage
that is changing
increasingly the games that matter are not zero-sum
there have long been games where you won by having new ideas
in the third century bc archimedes won by doing that
at least until an invading roman army killed him
and not just not being at war
people need to feel that what they create can't be stolen
that has always been the case for thinkers, which is why this trend began with them
the exciting thing is that their m
seems to be spreading
so i'm really glad i stopped to think about this
jessica and i have always worked hard to teach our kids not to be mean
we tolerate noise and mess and junk food, but not meanness
startups are very counterintuitive
i'm not sure why
maybe it's just because knowledge about them hasn't permeated our culture yet
but whatever the reason, starting a startup is a task where you can't always trust your instincts
it's like skiing in that way
when you first try skiing and you want to slow down, your instinct is to lean back
but if you lean back on skis you fly down the hill out of control
so part of learning to ski is learning to suppress that impulse
eventually you get new habits, but at first it takes a conscious effort
at first there's a list of things you're trying to remember as you start down the hill
startups are as unnatural as skiing, so there's a similar list for startups
counterintuitive
if you know nothing more than this, you may at least pause before making them
it's really true
they seem wrong
so of course your first impulse is to disregard them
if founders' instincts already gave them the right answers, they wouldn't need us
you only need other people to give you advice that surprises you
that's why there are a lot of ski instructors and not many running instructors
you can, however, trust your instincts about people
and in fact one of the most common mistakes young founders make is not to do that enough
if someone seems slippery, or bogus, or a jerk, don't ignore it
this is one case where it pays to be self-indulgent
work with people you genuinely like, and you've known long enough to be sure
the second counterintuitive point is that it's not that important to know a lot about startups
mark zuckerberg didn't succeed because he was an expert on startups
if you don't know anything about, say, how to raise an angel round, don't feel bad on that account
that sort of thing you can learn when you need to, and forget after you've done it
" it would set off alarms
from the outside that seems like what startups do
we saw this happen so often that we made up a name for it: playing house
eventually i realized why it was happening
think about what you have to do to get into college, for example
extracurricular activities, check
even in college classes most of the work is as artificial as running laps
i'm not attacking the educational system for being this way
i confess i did it myself in college
it was like a game
then they want to know what the tricks are for growing fast
and we have to tell them the best way to do that is simply to make something people want
" and the partner replying "just
gaming the system may continue to work if you go to work for a big company
[2] but that doesn't work with startups
startups are as impersonal as physics
you have to make something people want, and you prosper only to the extent you do
the dangerous thing is, faking does work to some degree on investors
but it's not in your interest to
the company is ultimately doomed
all you're doing is wasting your own time riding it down
so stop looking for the trick
it's exciting that there even exist parts of the world where you win by doing good work
how do you win in each type of work, and what would you like to win by doing? [4]
all-consuming
that brings us to our fourth counterintuitive point: startups are all-consuming
if you start a startup, it will take over your life to a degree you cannot imagine
so there is a real opportunity cost here
larry page may seem to have an enviable life, but there are aspects of it that are unenviable
if he goes on vacation for even a week, a whole week's backlog of shit accumulates
it never gets any easier
the nature of the problems change
but the total volume of worry never decreases; if anything it increases
many of which will make you a better parent when you do have kids
and since you can delay pushing the button for a while, most people in rich countries do
to be fair, the universities have their hand forced here
a lot of incoming students are interested in startups
universities are, at least de facto, expected to prepare them for their careers
so students who want to start startups hope universities can teach them about startups
can universities teach students about startups? yes and no
[5] so starting a startup is intrinsically something you can only really learn by doing it
you may be nominally a student for a bit, but you won't even be that for long
do not start a startup in college
starting a startup is like a brutally fast depth-first search
most people should still be searching breadth-first at 20
if you start a startup at 20 and you're sufficiently successful, you'll never get to do it
mark zuckerberg will never get to bum around a foreign country
he can do other things most people can't, like charter jets to fly him to foreign countries
but success has taken a lot of the serendipity out of his life
facebook is running him as much as he's running facebook
among other things it gives you more options to choose your life's work from
there's not even a tradeoff here
should you do it at any age? i realize i've made startups sound pretty hard
if i haven't, let me try again: starting a startup is really hard
what if it's too hard? how can you tell if you're up to this challenge?
the answer is the fifth counterintuitive point: you can't tell
starting a startup will change you a lot
it was easy to tell how smart they were, and most people reading this will be over that threshold
the hard part was predicting how tough and ambitious they would become
the founders sometimes think they know
if you're absolutely terrified of starting a startup, you probably shouldn't do it
but if you're merely unsure whether you're up to it, the only way to find out is to try
just not now
for getting both is the same
i've written a whole essay on this, so i won't repeat it all here
the way to come up with good startup ideas is to take a step back
in fact, so unconsciously that you don't even realize at first that they're startup ideas
this is not only possible, it's how apple, yahoo, google, and facebook all got started
none of these companies were even meant to be companies at first
they were all just side projects
the third part, incidentally, is how you get cofounders at the same time as the idea
" but that prescription, though sufficient, is too narrow
what was special about brian chesky and joe gebbia was not that they were experts in technology
what kind of problems are those? that is very hard to answer in the general case
so how do you know when you're working on real stuff? [8]
i know how i know
y combinator itself was something i only did because it seemed interesting
so i seem to have some sort of internal compass that helps me out
but i don't know what other people have in their heads
and indeed, probably also the best way to live
you may not realize they're startup ideas, but you'll know they're something that ought to exist
he didn't mean it to be a startup, and he never tried to turn it into one
" it's the classic version of college as education for its own sake
the component of entrepreneurship that really matters is domain expertise
the way to become larry page was to become an expert on search
at its best, starting a startup is merely an ulterior motive for curiosity
and you'll do it best if you introduce the ulterior motive toward the end of the process
most startups that raise money do it more than once
reality can be messier
some companies raise money twice in phase 2
others skip phase 1 and go straight to phase 2
but the three phase path is at least the one about which individual startups' paths oscillate
this essay focuses on phase 2 fundraising
that problem is irreducible; it should be hard
but much of the other kind of difficulty can be eliminated
you can't trust your intuitions
i'm going to give you a set of rules here that will get you through this process if anything will
at certain moments you'll be tempted to ignore them
so rule number zero is: these rules exist for a reason
the ultimate source of the forces acting on you are the forces acting on investors
but that fast growth means investors can't wait around
if you wait till a startup is obviously a success, it's too late
but that in turn makes investors nervous they're about to invest in a flop
as indeed they often are
what investors would like to do, if they could, is wait
but if you wait too long, other investors might take the deal away from you
and of course the other investors are all subject to the same forces
don't raise money unless you want it and it wants you
actually it isn't
rapid growth is what makes a company a startup
the other time not to raise money is when you won't be able to
be in fundraising mode or not
one of the things that surprises founders most about fundraising is how distracting it is
when you start fundraising, everything else grinds to a halt
the problem is not the time fundraising consumes but that it becomes the top idea in your mind
a startup can't endure that level of distraction for long
because fundraising is so distracting, a startup should either be in fundraising mode or not
you can take money from investors when you're not in fundraising mode
you just can't expend any attention on it
there are two things that take attention: convincing investors, and negotiating with them
[3] the terms will be whatever they turn out to be in your next equity round
investors will try to lure you into fundraising when you're not
it's great for them if they can, because they can thereby get a shot at you before everyone else
they'll send you emails saying they want to meet to learn more about you
deals don't happen that way
they may say they just want to meet and chat, but investors never just want to meet and chat
get introductions to investors
before you can talk to investors, you have to be introduced to them
if you're presenting at a demo day, you'll be introduced to a whole bunch simultaneously
but even if you are, you should supplement these with intros you collect yourself
do you have to be introduced? in phase 2, yes
intros vary greatly in effectiveness
the best type of intro is from a well-known investor who has just invested in you
so when you get an investor to commit, ask them to introduce you to other investors they respect
[7] the next best type of intro is from a founder of a company they've funded
you can also get intros from other people in the startup community, like lawyers and reporters
there are now sites like angellist, fundersclub, and wefunder that can introduce you to investors
we recommend startups treat them as auxiliary sources of money
raise money first from leads you get yourself
those will on average be better investors
hear no till you hear yes
i mentioned earlier that investors prefer to wait if they can
what's particularly dangerous for founders is the way they wait
essentially, they lead you on
they seem like they're about to invest right up till the moment they say no
if they even say no
some of the worse ones never actually do say no; they just stop replying to your emails
they hope that way to get a free option on investing
that's not the worst thing investors will do
and wishful thinking founders are happy to meet them half way
fortunately, the next rule is a tactic for neutralizing this behavior
but to work it depends on you not being tricked by the no that sounds like yes
if you believe an investor has committed, get them to confirm it
and till they confirm, regard them as saying no
do breadth-first search weighted by expected value
when you talk to investors your m
should be breadth-first search, weighted by expected value
you should always talk to investors in parallel rather than serially
meet such investors last, if at all
but you have to be disciplined about assigning probabilities
you can't let how much you want an investor influence your estimate of how much they want you
know where you stand
never leave a meeting with an investor without asking what happens next
if you're experienced at negotiations, you already know how to ask such questions
[13] if you're not, there's a trick you can use in this situation
investors know you're inexperienced at raising money
inexperience there doesn't make you unattractive
larry and sergey were noobs at fundraising
get the first commitment
the biggest factor in most investors' opinions of you is the opinion of other investors
once you start getting investors to commit, it becomes increasingly easy to get more to
but the other side of this coin is that it's often hard to get the first commitment
getting the first substantial offer can be half the total difficulty of fundraising
what counts as a substantial offer depends on who it's from and how much it is
money from friends and family doesn't usually count, no matter how much
close committed money
it's not a deal till the money's in the bank
and it's also one that furnishes them plenty of excuses to gratify it
the public markets snap startup investing around like a whip
if the chinese economy blows up tomorrow, all bets are off
tomorrow a big competitor could appear, or you could get cded, or your cofounder could quit
even a day's delay can bring news that causes an investor to change their mind
so when someone commits, get the money
knowing where you stand doesn't end when they say they'll invest
inexperienced investors are the ones most likely to get buyer's remorse
but i've heard of cases of even top-tier vc firms welching on deals
avoid investors who don't "lead
some investors are known for deciding quickly, and those are extra valuable early on
conversely, an investor who will only invest once other investors have is worthless initially
you can recognize this contemptible subspecies of investor because they often talk about "leads
" they say that they don't lead, or that they'll invest once you have a lead
now there are rarely actual rounds before the a round, or leads for them
now startups simply raise money from investors one at a time till they feel they have enough
the spectral signature of all mediocre investors
have multiple plans
many investors will ask how much you're planning to raise
this question makes founders feel they should be planning to raise a specific amount
but in fact you shouldn't
it's a mistake to have fixed plans in an undertaking as unpredictable as fundraising
" i've known a handful of founders who could pull that off without having vcs laugh in their faces
different plans match different investors
$15k per month is high, so don't actually spend that much
but it's ok to use a high estimate when fundraising to add a margin for error
if you have additional expenses, like manufacturing, add in those at the end
underestimate how much you want
then when you reach $150k you're more than half done
whereas if you'd said you were raising $500k, you'd be less than a third done at $150k
if fundraising stalled there for an appreciable time, you'd start to read as a failure
saying initially that you're raising $250k doesn't limit you to raising that much
startups do that all the time
i'm not saying you should lie, but that you should lower your expectations initially
there is almost no downside in starting with a low number
it not only won't cap the amount you raise, but will on the whole tend to increase it
a good metaphor here is angle of attack
if you try to fly at too steep an angle of attack, you just stall
be profitable if you can
if you can make it to profitability without raising any additional money
there are many analogies between fundraising and dating, and this is one of the strongest
no one wants you if you seem desperate
and the best way not to seem desperate is not to be desperate
and they are then surprised how difficult and unpleasant it is
of course not all startups can make it to ramen profitability in a few months
don't optimize for valuation
founders who raise money at high valuations tend to be unduly proud of it
this is stupid, because fundraising is not the test that matters
the real test is revenue
fundraising is just a means to that end
being proud of how well you did at fundraising is like being proud of your college grades
number two is good investors
valuation is at best third
the empirical evidence shows just how unimportant it is
6 million respectively
so let that satisfy your competitiveness
you're doing better than dropbox and airbnb at a test that doesn't matter
it will be easier to raise money at a lower valuation
it shouldn't be, but it is
but although it's a mistake for investors to care about price, a significant number do
yesno before valuation
some investors want to know what your valuation is before they even talk to you about investing
fortunately there is a way to avoid naming a price in this situation
and it is not just a negotiating trick; it's how you (both) should be operating
then if they decide they do want to invest, you can figure out a price
but first things first
this is a safe technique so long as you combine it with the next one
beware "valuation sensitive" investors
occasionally you'll encounter investors who describe themselves as "valuation sensitive
you should therefore never approach such investors first
this way, you'll not only get market price, but it will also take less time
so you'd only want to talk to this sort of investor if you were about to do that anyway
if you're surprised by a lowball offer, treat it as a backup offer and delay responding to it
but lowballing you is a dick move that should be met with the corresponding countermove
accept offers greedily
a greedy algorithm takes the best of the options in front of it right now
and that is how startups should approach fundraising in phases 2 and later
if someone makes you an acceptable offer, take it
if you have multiple incompatible offers, take the best
don't reject an acceptable offer in the hope of getting a better one in the future
these simple rules cover a wide variety of cases
if you're raising money from many investors, roll them up as they say yes
as you start to feel you've raised enough, the threshold for acceptable will start to get higher
in practice offers exist for stretches of time, not points
so when you get an acceptable offer that would be incompatible with others (e
this could lose you some that might have made an offer if they had more time
but by definition you don't care; the initial offer was acceptable
a deadline of three working days is acceptable
you shouldn't need more than that if you've been talking to investors in parallel
but a deadline any shorter is a sign you're dealing with a sketchy investor
you can usually call their bluff, and you may need to
but if it does, "get the best investors" is in the average case bad advice
the best investors are also the most selective, because they get their pick of all the startups
(the situation is different in phase 1
there's no practical difficulty
if the smaller investments are on convertible notes, they'll just convert into the series a round
till they do, you don't know for sure they will, and the greedy algorithm tells you what to do
don't sell more than 25% in phase 2
if you do well, you will probably raise a series a round eventually
i say probably because things are changing with series a rounds
startups may start to skip them
which means you should avoid doing things in earlier rounds that will mess up raising an a round
guess conservatively
have one person handle fundraising
(if the founders mistrust one another, this could cause some friction
even if the ceo is a programmer and another founder is a salesperson? yes
but wait till that point
you'll need an executive summary and (maybe) a deck
traditionally phase 2 fundraising consists of presenting a slide deck in person to investors
a lot of the most successful startups we fund never make decks in phase 2
they just talk to investors and explain what they plan to do
but don't refuse on that account to give copies to investors you meet
you just have to treat such leaks as a cost of doing business
in practice it's not that high a cost
i wouldn't do that
it's a sign they're not really interested
stop fundraising when it stops working
when do you stop fundraising? ideally when you've raised enough
but what if you haven't raised as much as you'd like? when do you give up?
when your fundraising options run out, they usually run out in the same way
don't keep sucking on the straw if you're just getting air
it's not going to get better
don't get addicted to fundraising
the work at an early stage startup often consists of unglamorous schleps
whereas fundraising, when it's going well, can be quite the opposite
the danger of fundraising is particularly acute for people who are good at it
it's always fun to work on something you're good at
if you're one of these people, beware
fundraising is not what will make your company successful
listening to users complain about bugs in your software is what will make you successful
startups can be destroyed by this
don't raise too much
though only a handful of startups have to worry about this, it is possible to raise too much
the dangers of raising too much are subtle but insidious
one is that it will set impossibly high expectations
a company's valuation is expected to rise each time it raises money
if not it's a sign of a company in trouble, which makes you unattractive to investors
and you have to be doing really, really well to raise money at $50 million
but the money itself may be more dangerous than the valuation
so if you do raise a huge amount of money, don't spend it
startups raising money occasionally alienate investors by seeming arrogant
it's a mistake to behave arrogantly to investors
the only safe strategy is never to seem arrogant at all
so you must cushion the blow with soft words
at yc we tell startups they can blame us
and now that i've written this, everyone else can blame me if they want
the danger of behaving arrogantly is greatest when you're doing well
when everyone wants you, it's hard not to let it go to your head
especially if till recently no one wanted you
but restrain yourself
the startup world is a small place, and startups have lots of ups and downs
this is a domain where it's more true than usual that pride goeth before a fall
be nice when investors reject you as well
the best investors are not wedded to their initial opinion of you
if they reject you in phase 2 and you end up doing well, they'll often invest in phase 3
in fact investors who reject you are some of your warmest leads for future fundraising
any investor who spent significant time deciding probably came close to saying yes
the bar will be higher next time
assume the money you raise in phase 2 will be the last you ever raise
you must make it to profitability on this money if you can
this is probably the optimal strategy for investors
it's too hard to pick winners early on
better to let the market do it for you
but it often comes as a surprise to startups how much harder it is to raise money in phase 3
the next time you raise money, the experiment has to have worked
you have to be on a trajectory that leads to going public
and while there are some ideas where the proof that the experiment worked might consist of e
query response times, usually the proof is profitability
usually phase 3 fundraising has to be type a fundraising
in practice there are two ways startups hose themselves between phases 2 and 3
some are just too slow to become profitable
they raise enough money to last for two years
there doesn't seem any particular urgency to be profitable
so they don't make any effort to make money for a year
but by that time, not making money has become habitual
when they finally decide to try, they find they can't
the other way companies hose themselves is by letting their expenses grow too fast
which almost always means hiring too many people
you usually shouldn't go out and hire 8 people as soon as you raise money at phase 2
usually you want to wait till you have growth (and thus usually revenues) to justify them
a lot of vcs will encourage you to hire aggressively
don't listen to them
don't make things complicated
that's fundraising in one sentence
don't introduce complicated optimizations, and don't let investors introduce complications either
fundraising is not what will make you successful
it's just a means to an end
be good, take care of yourselves, and don't leave the path
the biggest component in most investors' opinion of you is the opinion of other investors
which is of course a recipe for exponential growth
but actually the two are not that highly correlated
if you understand them, you can at least avoid being surprised
raising money decreases the risk of failure
plus a company that has raised money is literally more valuable
though they're often clueless about technology, most investors are pretty good at reading people
when fundraising is going well, investors are quick to sense it in your increased confidence
judging startups is hard even for the best investors
the mediocre ones might as well be flipping coins
the best investors aren't influenced much by the opinion of other investors
it would only dilute their own judgment to average it together with other people's
this is the fourth way in which offers beget offers
founders try this sort of thing all the time, and investors are very sensitive to it
if anything oversensitive
but you're safe so long as you're telling the truth
there's no manipulation in that
do not, however, tell a who b is
vcs will sometimes ask which other vcs you're talking to, but you should never tell them
angels you can sometimes tell about other angels, because angels cooperate more with one another
the second will be easier
the right way to lift heavy things is to let your legs do the work
inexperienced founders make the same mistake when trying to convince investors
they try to convince with their pitch
investors are looking for startups that will be very successful
but that test is not as simple as it sounds
the big successes are so big they dwarf the rest
but angel investors like big successes too
the most important ingredient is formidable founders
[2] every startup has reasons both to invest and not to invest
if investors think you're a winner they focus on the former, and if not they focus on the latter
for example, it might be a rich market, but with a slow sales cycle
they're not necessarily trying to mislead you
most investors are genuinely unclear in their own minds why they like or dislike startups
if you seem like a winner, they'll like your idea more
but don't be too smug about this weakness of theirs, because you have it too; almost everyone does
there is a role for ideas of course
they're fuel for the fire that starts with liking the founders
" (whereas when they don't like you, they'll be saying "but what about x?")
formidable is close to confident, except that someone could be confident and mistaken
formidable is roughly justifiably confident
what should they do? [4]
what they should not do is try to imitate the swagger of more experienced founders
investors are not always that good at judging technology, but they're good at judging confidence
if you try to act like something you're not, you'll just end up in an uncanny valley
you'll depart from sincere, but never arrive at convincing
the way to seem most formidable as an inexperienced founder is to stick to the truth
how formidable you seem isn't a constant
it varies depending on what you're saying
that's the secret
and by convince yourself, i don't mean play mind games with yourself to boost your confidence
i mean truly evaluate whether your startup is worth investing in
if it isn't, don't try to raise money
to evaluate whether your startup is worth investing in, you have to be a domain expert
which in fact it will usually be
know everything about your market
when the unfortunate fellow got to his last slide, the professor burst out:
which one of these conclusions do you actually believe?
even if you have no ideas
you have to produce something
and all too many startups go into fundraising in the same spirit
it's when you can convince investors, and not before
if you try convincing investors before you've convinced yourself, you'll be wasting both your time
but pausing first to convince yourself will do more than save you from wasting your time
it will force you to organize your thoughts
and if you can do that you'll end up with more than added confidence
you'll also have a provisional roadmap of how to succeed
no one knows whether a startup is going to succeed
startup investors know that every investment is a bet, and against pretty long odds
founders think of startups as ideas, but investors think of them as markets
your target market has to be big, and it also has to be capturable by you
but the market doesn't have to be big yet, nor do you necessarily have to be in it yet
the standard of plausibility varies dramatically depending on the age of the startup
microsoft for example was not going to grow huge selling basic interpreters
good, but not great
no company, however successful, ever looks more than a pretty good bet a few months in
microcomputers turned out to be a big deal, and microsoft both executed well and got lucky
but it was by no means obvious that this was how things would play out
plenty of companies seem as good a bet a few months in
and who can reasonably expect more of a startup than that?
if you can make as good a case as microsoft could have, will you convince investors? not always
a lot of vcs would have rejected microsoft
[9] certainly some rejected google
this is arguably a permissible tactic
it's arguably an instance of scamming a scammer
if you know you're on the right track, then you also know why investors were wrong to reject you
experienced investors are well aware that the best ideas are also the scariest
they all know about the vcs who rejected google
that's what happened to dropbox
yet another backup and syncing thing, they all thought
a couple weeks later, dropbox raised a series a round from sequoia
you can convince yourself, then convince them
and when you convince them, use the same matter-of-fact language you used to convince yourself
you wouldn't use vague, grandiose marketing-speak among yourselves
don't use it with investors either
it not only doesn't work on them, but seems a mark of incompetence
just be concise
so here's the recipe for impressing investors when you're not already good at seeming formidable:
make something worth investing in
understand why it's worth investing in
explain that clearly to investors
if you're saying something you know is true, you'll seem confident when you're saying it
conversely, never let pitching draw you into bullshitting
as long as you stay on the territory of truth, you're strong
make the truth good, then just tell it
one of the most common types of advice we give at y combinator is to do things that don't scale
a lot of would-be founders believe that startups either take off or don't
or they don't, in which case the market must not exist
actually startups take off because the founders make them take off
a good metaphor would be the cranks that car engines had before they got electric starters
the most common unscalable thing founders have to do at the start is to recruit users manually
nearly all startups have to
you can't wait for users to come to you
you have to go out and get them
if anyone could have sat back and waited for users, it was stripe
but in fact they're famous within yc for aggressive early user acquisition
at yc we use the term "collison installation" for the technique they invented
" but the collison brothers weren't going to wait
there are two reasons founders resist going out and recruiting users individually
one is a combination of shyness and laziness
the other reason founders ignore this path is that the absolute numbers seem so small at first
this can't be how the big, famous startups got started, they think
the mistake they make is to underestimate the power of compound growth
we encourage every startup to measure their progress by weekly growth rate
if you have 100 users, you need to get 10 more next week to grow 10% a week
after a year you'll have 14,000 users, and after 2 years you'll have 2 million
airbnb is a classic example of this technique
marketplaces are so hard to get rolling that you should expect to take heroic measures at first
that initial fragility was not a unique feature of airbnb
almost all startups are fragile initially
they unconsciously judge larval startups by the standards of established ones
it's harmless if reporters and know-it-alls dismiss your startup
they always get things wrong
it's even ok if investors dismiss your startup; they'll change their minds when they see growth
the big danger is that you'll dismiss your startup yourself
i've seen it happen
i often have to encourage founders who don't see the full potential of what they're building
even bill gates made that mistake
he returned to harvard for the fall semester after starting microsoft
they were just trying to survive
but in retrospect that too was the optimal path to dominating a big market
otherwise you'll have to make a more deliberate effort to locate the most promising vein of users
you should take extraordinary measures not just to acquire users, but also to make them happy
your first users should feel that signing up with you was one of the best choices they ever made
and you in turn should be racking your brains to think of new ways to delight them
you can be ornery when you're scotty, but not when you're kirk
that would be a great problem to have
see if you can make it happen
tim cook doesn't send you a hand-written note after you buy a laptop
but you can
that's one advantage of being small: you can provide a level of service no big company can
steve wasn't just using "insanely" as a synonym for "very
what novice founders don't get is what insanely great translates to in a larval startup
when steve jobs started using that phrase, apple was already an established company
that's not hard for engineers to grasp
it's just a more extreme version of designing a robust and elegant product
it's not the product that should be insanely great, but the experience of being your user
the product is just one component of that
for a big company it's necessarily the dominant one
can, perhaps, but should? yes
over-engaging with early users is not just a permissible technique for getting growth rolling
making a better mousetrap is not an atomic operation
the feedback you get from engaging directly with your earliest users will be the best you ever get
sometimes the right unscalable trick is to focus on a deliberately narrow market
it's like keeping a fire contained at first to get it really hot before adding more logs
that's what facebook did
at first it was just for harvard students
most startups that use the contained fire strategy do it unconsciously
the strategy works just as well if you do it unconsciously
among companies, the best early adopters are usually other startups
plus when they succeed they grow fast, and you with them
they got started by doing something that really doesn't scale: assembling their routers themselves
hardware startups face an obstacle that software startups don't
the minimum order for a factory production run is usually several hundred thousand dollars
the arrival of crowdfunding (or more precisely, preorders) has helped a lot
but even so i'd advise startups to pull a meraki initially if they can
that's what pebble did
the pebbles assembled the first several hundred watches themselves
" who knew?
even if there aren't many of them, there are probably adjacent territories that have more
consulting is the canonical example of work that doesn't scale
that's where companies cross the line
we did that at viaweb
since we would do anything to get users, we did
we felt pretty lame at the time
there's a more extreme variant where you don't just use your software, but are your software
some startups could be entirely manual at first
i should mention one sort of initial tactic that usually doesn't work: the big launch
they want to launch simultaneously in 8 different publications, with embargoes
and on a tuesday, of course, since they read somewhere that's the optimum day to launch something
it's easy to see how little launches matter
think of some successful startups
so why do founders think launches matter? a combination of solipsism and laziness
partnerships too usually don't work
it's not enough just to do something extraordinary initially
you have to make an extraordinary effort initially
y combinator has now funded 564 startups including the current batch, which has 53
7 billion, and the 511 prior to the current batch have collectively raised about $1
as usual those numbers are dominated by a few big winners
the top 10 startups account for 8
6 of that 11
but there is a peloton of younger startups behind them
there are about 40 more that have a shot at being really big
i'd guess we can grow another 2 or 3x before hitting the next bottleneck
one consequence of funding such a large number of startups is that we see trends early
i'm going to take a shot at describing where these trends are leading
i think more
now there's a third: start your own company
that's a big change
i think we're still at the beginning of this one
it's hard to predict how big a deal it will be
as big a deal as the industrial revolution? maybe
probably not
one thing we can say for sure is that there will be a lot more startups
this process is not just something happening now in silicon valley
it started decades ago, and it's happening as far afield as the car industry
it has a long way to run
the other big driver of change is that startups are becoming cheaper to start
which means investors will get less stock and less control
there are still a lot of people who'd make great founders who never end up starting a company
you can see that from how randomly some of the most successful startups got started
there might be 10x or even 50x more good founders out there
high returns don't come from investing at low valuations
they come from investing in the companies that do really well
so if there are more of those to be had each year, the best pickers should have more hits
this means there should be more variability in the vc business
whereas the bad firms will get the leftovers, as they do now, and yet pay a higher price for them
nor do i think it will be a problem that founders keep control of their companies for longer
what about angels? i think there is a lot of opportunity there
it used to suck to be an angel investor
and the days when vcs could wash angels out of the cap table are long gone
few investors understand the cost that raising money from them imposes on startups
and in this context, low-cost means deciding quickly
one is that the scariness of starting a startup in the old days was a pretty effective filter
now that the cost of failing is becoming lower, we should expect founders to do it more
that's not a bad thing
it will be interesting, in a bad way, if idea clashes become a lot more common
what used to be an obelisk will become a pyramid
it will be a little wider at the top, but a lot wider at the bottom
imagine the obelisk of investors that corresponds to the obelisk of startups
i think the biggest danger for vcs, and also the biggest opportunity, is at the series a stage
right now, vcs often knowingly invest too much money at the series a stage
some vcs lie and claim the company really needs that much
like a lot of bad things, this didn't happen intentionally
the vc business backed into it as their initial assumptions gradually became obsolete
what will happen to the vc business when that happens? hell if i know
but i bet that particular firm will end up ahead
and that's where the money is
you can't fight market forces forever
40% used to be common
now vcs are fighting to hold the line at 20%
but i am daily waiting for the line to collapse
it's going to happen
you may as well anticipate it, and look bold
who knows, maybe vcs will make more money by doing the right thing
it wouldn't be the first time that happened
venture capital is a business where occasional big successes generate hundredfold returns
if you want to find new opportunities for investing, look for things founders complain about
founders are your customers, and the things they complain about are unsatisfied demand
but the more general recipe is: do something founders want
the way to get startup ideas is not to try to think of startup ideas
it's to look for problems, preferably problems you have yourself
microsoft, apple, yahoo, google, and facebook all began this way
it sounds obvious to say you should only work on problems that exist
and yet by far the most common mistake startups make is to solve problems no one has
i made it myself
in 1995 i started a company to put art galleries online
but galleries didn't want to be online
it's not how the art business works
so why did i spend 6 months working on this stupid idea? because i didn't pay attention to users
i invented a model of the world that didn't correspond to reality, and worked from that
i didn't notice my model was wrong until i tried to convince users to pay for what we'd built
even then i took embarrassingly long to catch on
i was attached to my model of the world, and i'd spent a lot of time on the software
they had to want it
at yc we call these "made-up" or "sitcom" startup ideas
imagine one of the characters on a tv show was starting a startup
the writers would have to invent something for it to do
but coming up with good startup ideas is hard
it's not something you can do for the asking
for example, a social network for pet owners
it doesn't sound obviously mistaken
millions of people have pets
often they care a lot about their pets and spend a lot of money on them
surely many of these people would like a site where they could talk to other pet owners
you could serve them targeted offers, and maybe charge for premium features
" they say "yeah, maybe i could see using something like that
" even when the startup launches, it will sound plausible to a lot of people
sum that reaction across the entire population, and you have zero users
choose the latter
if you invert the scale on the y axis, you can envision companies as holes
google is an immense crater: hundreds of millions of people use it, and they need it a lot
a startup just starting out can't expect to excavate that much volume
so you have two choices about the shape of hole you start with
you can either dig a hole that's broad but shallow, or one that's narrow and deep, like a well
made-up startup ideas are usually of the first type
lots of people are mildly interested in a social network for pet owners
nearly all good startup ideas are of the second type
microsoft was a well when they made altair basic
thirty years later facebook had the same shape
you don't need the narrowness of the well per se
it's depth you need; you get narrowness as a byproduct of optimizing for depth (and speed)
but you almost always do get it
facebook was a good idea because it started with a small market there was a fast path out of
so you spread rapidly through all the colleges
once you have all the college students, you get everyone else simply by letting them in
the founders of airbnb didn't realize at first how big a market they were tapping
initially they had a much narrower idea
they were going to let hosts rent out space on their floors during conventions
they didn't foresee the expansion of this idea; it forced itself upon them gradually
all they knew at first is that they were onto something
that's probably as much as bill gates or mark zuckerberg knew at first
occasionally it's obvious from the beginning when there's a path out of the initial niche
and sometimes i can see a path that's not immediately obvious; that's one of our specialties at yc
but there are limits to how well this can be done, no matter how much experience you have
in zen and the art of motorcycle maintenance, robert pirsig says:
you want to know how to paint a perfect painting? it's easy
make yourself perfect and then just paint naturally
i've wondered about that passage since i read it in high school
i'm not sure how useful his advice is for painting specifically, but it fits this situation well
empirically, the way to have good startup ideas is to become the sort of person who has them
you can also be at the leading edge as a user
but mark already lived online; to him it seemed natural
paul buchheit says that people at the leading edge of a rapidly changing field "live in the future
" combine that with pirsig and you get:
live in the future, then build what's missing
that describes the way many if not most of the biggest startups got started
neither apple nor yahoo nor google nor facebook were even supposed to be companies at first
they grew out of things their founders built because there seemed a gap in the world
" lots of people heard about the altair
lots forgot usb sticks
the verb you want to be using with respect to startup ideas is not "think up" but "notice
the most successful startups almost all begin this way
that may not have been what you wanted to hear
but disappointing though it may be, this is the truth
and it is a recipe of a sort, just one that in the worst case takes a year rather than a weekend
if you're not at the leading edge of some rapidly changing field, you can get to one
for example, anyone reasonably smart can probably get to an edge of programming (e
building mobile apps) in a year
especially if you're also looking for a cofounder
you don't have to learn programming to be at the leading edge of a domain that's changing fast
other domains change fast
but while learning to hack is not necessary, it is for the forseeable future sufficient
as marc andreessen put it, software is eating the world, and this trend has decades left to run
knowing how to hack also means that when you have ideas, you'll be able to implement them
that's not absolutely necessary (jeff bezos couldn't) but it's an advantage
i'll try building an initial version tonight
what won't be obvious is that they're startup ideas
most things that are missing will take some time to see
you almost have to trick yourself into seeing the ideas around you
but you know the ideas are out there
this is not one of those problems where there might not be an answer
it's impossibly unlikely that this is the exact moment when technological progress stops
and when these problems get solved, they will probably seem flamingly obvious in retrospect
what you need to do is turn off the filters that usually prevent you from seeing them
the most powerful is simply taking the current state of the world for granted
even the most radically open-minded of us mostly do that
you couldn't get from your bed to the front door if you stopped to question everything
pay particular attention to things that chafe you
when something annoys you, it could be because you're living in the future
it was obvious to us as programmers that these sites would have to be generated by software
to sit down and try to think of ideas
give yourself some time
drew houston did work on a less promising idea before dropbox: an sat prep startup
but dropbox was a much better idea, both in the absolute sense and also as a match for his skills
if you do that, you'll naturally tend to build things that are missing
it wouldn't seem as interesting to build something that already existed
it's cool; users love it; it just doesn't matter
microcomputers seemed like toys when apple and microsoft started working on them
" backrub seemed like an inconsequential science project
the facebook was just a way for undergrads to stalk one another
to us that's positive evidence an idea is good
live in the future and build what seems interesting
that's what i'd advise college students to do, rather than trying to learn about "entrepreneurship
" "entrepreneurship" is something you learn best by doing it
the examples of the most successful founders make that clear
what you should be spending your time on in college is ratcheting yourself into the future
college is an incomparable opportunity to do that
all you'll learn is the words for things
the clash of domains is a particularly fruitful source of ideas
or better still, go work for a biotech company
cs majors normally get summer jobs at computer hardware or software companies
or don't take any extra classes, and just build things
it's no coincidence that microsoft and facebook both got started in january
but don't feel like you have to build things that will become startups
that's premature optimization
just build things
preferably with other students
you're also surrounded by other people trying to do the same thing
beware of research
whereas a phd dissertation is extremely unlikely to
competition
because a good idea should seem obvious, when you have one you'll tend to feel that you're late
don't let that deter you
worrying that you're late is one of the signs of a good idea
ten minutes of searching the web will usually settle the question
even if you find someone else working on the same thing, you're probably not too late
if you're uncertain, ask users
the question then is whether that beachhead is big enough
err on the side of doing things where you'll face competitors
inexperienced founders usually give competitors more credit than they deserve
whether you succeed depends far more on you than on your competitors
so better a good idea with competitors than a bad one without
in fact that's a very promising starting point
google was that type of idea
your thesis has to be more precise than "we're going to make an x that doesn't suck" though
you have to be able to phrase it in terms of something the incumbents are overlooking
google was that type of idea too
they'd prefer not to deal with tedious problems or get involved in messy ways with the real world
which is a reasonable preference, because such things slow you down
and dealing with payments is a schlep for stripe, but not an intolerable one
we overcame this one to work on viaweb
we could see the problem was one that needed to be solved though
and even to the degree it isn't, it's a worse form of self-indulgence
starting a successful startup is going to be fairly laborious no matter what
the unsexy filter, while still a source of error, is not as entirely useless as the schlep filter
particularly as you get older and more experienced
plus if you find an idea sexy, you'll work on it more enthusiastically
sometimes you need an idea now
for example, if you're working on a startup and your initial idea turns out to be bad
for the rest of this essay i'll talk about tricks for coming up with startup ideas on demand
although empirically you're better off using the organic strategy, you could succeed this way
you just have to be more disciplined
you'll see a lot more ideas, most of them bad, so you need to be able to filter them
one of the biggest dangers of not using the organic method is the example of the organic method
organic ideas feel like inspirations
when searching for ideas, look in areas where you have some expertise
if you're a database expert, don't build a chat app for teenagers (unless you're also a teenager)
maybe it's a good idea, but you can't trust your judgment about that, so ignore it
there have to be other ideas that involve databases, and whose quality you can judge
the place to start looking for ideas is things you need
there must be things you need
" if you can think of any x people said that about, you probably have an idea
you know there's demand, and people don't say that about things that are impossible to build
you're probably not the only one
it's especially good if you're different in a way people will increasingly be
if you're changing ideas, one unusual thing about you is the idea you'd previously been working on
did you discover any needs while working on it? several well-known startups began this way
a particularly promising way to be unusual is to be young
some of the most valuable new ideas take root first among people in their teens and early twenties
it would have been very hard for someone who wasn't a college student to start facebook
the next best thing to an unmet need of your own is an unmet need of someone else
try talking to everyone you can about the gaps they find in the world
you're just looking for something to spark a thought
when you find an unmet need that isn't your own, it may be somewhat blurry at first
the person who needs something may not know exactly what they need
one way to ensure you do a good job solving other people's problems is to make them your own
that may seem like taking things to extremes, but startups are extreme
we love it when founders do such things
don't try to start twitter
those ideas are so rare that you can't find them by looking for them
make something unsexy that people will pay you for
what would you pay for right now?
for example, journalism is in free fall at the moment
but there may still be money to be made from something like journalism
but imagine asking that in the future, not now
when one company or industry replaces another, it usually comes in from the side
and be imaginative about the axis along which the replacement occurs
it could be replaced on any of these axes (it has already started to be on most)
the prices of gene sequencing and 3d printing are both experiencing moore's law-like declines
looking for waves is essentially a way to simulate the organic method
finding startup ideas is a subtle business, and that's why most people who try fail so miserably
it doesn't work well simply to try to think of startup ideas
if you do that, you get bad ones that sound dangerously plausible
but even then, not immediately
it takes time to come across situations where you notice something missing
live in the future and build what seems interesting
strange as it sounds, that's the real recipe
one advantage of y combinator's early, broad focus is that we see trends before most other people
and one of the most conspicuous trends in the last batch was the large number of hardware startups
out of 84 companies, 7 were making hardware
on the whole they've done better than the companies that weren't
they've faced resistance from investors of course
investors have a deep-seated bias against hardware
but investors' opinions are a trailing indicator
there is no one single force driving this trend
hardware does well on crowdfunding sites
electric motors have improved
wireless connectivity of various types can now be taken for granted
it's getting more straightforward to get things manufactured
retailers are less of a bottleneck as customers increasingly buy online
one question i can answer is why hardware is suddenly cool
it always was cool
physical things are great
they just haven't been as great a way to start a rapidly growing business as software
but that rule may not be permanent
it's not even that old; it only dates from about 1990
maybe the advantage of software will turn out to have been temporary
hackers love to build hardware, and customers love to buy it
it wouldn't be the first time something was a bad idea till it wasn't
and it wouldn't be the first time investors learned that lesson from founders
a startup is a company designed to grow fast
being newly founded does not in itself make a company a startup
" the only essential thing is growth
everything else we associate with startups follows from growth
if you want to start one it's important to understand that
startups are so hard that you can't be pointed off to the side and hope to succeed
you have to know that growth is what you're after
the good news is, if you get growth, everything else tends to fall into place
which means you can use growth like a compass to make almost every decision you face
millions of companies are started every year in the us
only a tiny fraction are startups
most are service businessesrestaurants, barbershops, plumbers, and so on
these are not startups, except in a few unusual cases
a barbershop isn't designed to grow fast
whereas a search engine, for example, is
when i say startups are designed to grow fast, i mean it in two senses
partly i mean designed in the sense of intended, because most startups fail
that difference is why there's a distinct word, "startup," for companies designed to grow fast
we could just talk about super-successful companies and less successful ones
but in fact startups do have a different sort of dna from other businesses
google is not just a barbershop whose founders were unusually lucky and hard-working
google was different from the beginning
to grow rapidly, you need to make something you can sell to a big market
that's the difference between google and a barbershop
a barbershop doesn't scale
barbershops are doing fine in the (a) department
almost everyone needs their hair cut
the problem for a barbershop, as for any retail establishment, is (b)
a barbershop serves customers in person, and few will travel far for a haircut
and even if they did the barbershop couldn't accomodate them
writing software is a great way to solve (b), but you can still end up constrained in (a)
if you make software to teach english to chinese speakers, however, you're in startup territory
most businesses are tightly constrained in (a) or (b)
the distinctive feature of successful startups is that they're not
it might seem that it would always be better to start a startup than an ordinary business
if you write software to teach tibetan to hungarians, you won't have much competition
the constraints that limit ordinary companies also protect them
that's the tradeoff
if you start a barbershop, you only have to compete with other local barbers
if you start a search engine you have to compete with the whole world
bar neighborhood is a sufficient idea for a small business
similarly for companies constrained in (a)
your niche both protects and defines you
but that's not how most startups get started
[3] but at the moment when successful startups get started, much of the innovation is unconscious
what's different about successful founders is that they can see different problems
steve wozniak's problem was that he wanted his own computer
that was an unusual problem to have in 1975
but technological change was about to make it a much more common one
google has similar origins
larry page and sergey brin wanted to search the web
that's one connection between startup ideas and technology
rapid change in one area uncovers big, soluble problems in other areas
sometimes the changes are advances, and what they change is solubility
but in google's case the most important change was the growth of the web
what changed there was not solubility but bigness
how fast does a company have to grow to be considered a startup? there's no precise answer to that
"startup" is a pole, not a threshold
starting one is at first no more than a declaration of one's ambitions
but at first you have no more than commitment
starting a startup is like being an actor in that respect
"actor" too is a pole rather than a threshold
at the beginning of his career, an actor is a waiter who goes to auditions
the growth of a successful startup usually has three phases:
eventually a successful startup will grow into a big company
together these three phases produce an s-curve
the phase whose growth defines the startup is the second one, the ascent
its length and slope determine how big the company will be
the slope is the company's growth rate
if there's one number every founder should always know, it's the company's growth rate
that's the measure of a startup
if you don't know that number, you don't even know if you're doing well or badly
" that's not a rate
a good growth rate during yc is 5-7% a week
if you can hit 10% a week you're doing exceptionally well
if you can only manage 1%, it's a sign you haven't yet figured out what you're doing
the best thing to measure the growth rate of is revenue
the next best, for startups that aren't charging initially, is active users
the key word here is "just
" if they decide to grow at 7% a week and they hit that number, they're successful for that week
there's nothing more they need to do
programmers will recognize what we're doing here
we're turning starting a startup into an optimization problem
you don't have to think about what the program should do, just make it faster
for most programmers this is very satisfying work
judging yourself by weekly growth doesn't mean you can look no more than a week ahead
it's not that you don't think about the future, just that you think about it no more than necessary
in theory this sort of hill-climbing could get a startup into trouble
they could end up on a local maximum
but in practice that never happens
nine times out of ten, sitting around strategizing is just a form of procrastination
whereas founders' intuitions about which hill to climb are usually better than they realize
plus the maxima in the space of startup ideas are not spiky and isolated
most fairly good ideas are adjacent to even better ones
the fascinating thing about optimizing for growth is that it can actually discover startup ideas
you can use the need for growth as a form of evolutionary pressure
there's a parallel here to small businesses
for startups, growth is a constraint much like truth
every successful startup is at least partly a product of the imagination of growth
if we project forward we see why
weeklyyearly
a company that grows at 1% a week will grow 1
7x a year, whereas a company that grows at 5% a week will grow 12
a startup that grows at 5% a week will in 4 years be making $25 million a month
what happens to fast growing startups tends to surprise even the founders
small variations in growth rate produce qualitatively different outcomes
and, strangely enough, it's also why they fail so frequently
for the right peoplee
the young bill gatesthe probability might be 20% or even 50%
so it's not surprising that so many want to take a shot at it
and since the latter is huge the former should be too
this doesn't bother me
it's the same with other high-beta vocations, like being an actor or a novelist
i've long since gotten used to it
but it seems to bother a lot of people, particularly those who've started ordinary businesses
if they stepped back and looked at the whole picture they might be less indignant
if you judge by the median startup, the whole concept of a startup seems like a fraud
but it's a mistake to use the median in a domain with so much variation
the test of any investment is the ratio of return to risk
but that's not the only reason investors like startups
the other way to get returns from an investment is in the form of dividends
the founders can't enrich themselves without also enriching the investors
why do founders want to take the vcs' money? growth, again
the constraint between good ideas and growth operates in both directions
it's not merely that you need a scalable idea to grow
if you have such an idea and don't grow fast enough, competitors will
almost every company needs some amount of funding to get started
but startups often raise money even when they are or could be profitable
fundamentally that's how the most successful startups view fundraising
raising money lets you choose your growth rate
a profitable startup could if it wanted just grow on its own revenues
growing slower might be slightly dangerous, but chances are it wouldn't kill them
pretty much every successful startup will get acquisition offers too
why? what is it about startups that makes other companies want to buy them? [13]
but acquirers have an additional reason to want startups
a rapidly growing company is not merely valuable, but dangerous
if it keeps expanding, it might expand into the acquirer's own territory
most product acquisitions have some component of fear
the combination of founders, investors, and acquirers forms a natural ecosystem
just as our ancestors did to explain the apparently too neat workings of the natural world
but there is no secret cabal making it all work
to anyone who knows mark zuckerberg that is the reductio ad absurdum of the initial assumption
if you want to understand startups, understand growth
growth drives everything in this world
and growth explains why successful startups almost invariably get acquisition offers
to acquirers a fast-growing company is not merely valuable but dangerous too
understanding growth is what starting a startup consists of
you're committing to search for one of the rare ideas that generates rapid growth
because these ideas are so valuable, finding one is hard
the startup is the embodiment of your discoveries so far
a startup founder is in effect an economic research scientist
most don't discover anything that remarkable, but some discover relativity
the first rule i knew intellectually, but didn't really grasp till it happened to us
the total value of the companies we've funded is around 10 billion, give or take a few
but just two companies, dropbox and airbnb, account for about three quarters of it
in startups, the big winners are big to a degree that violates our expectations about variation
that yields all sorts of strange consequences
and yet it's true
[2] you need to do what you know intellectually to be right, even though it feels wrong
it's a constant battle for us
it's hard to make ourselves take enough risks
when you interview a startup and think "they seem likely to succeed," it's hard not to fund them
their chances of succeeding seem small
unfortunately picking winners is harder than that
that's made harder by the fact that the best startup ideas seem at first like bad ideas
so the most successful founders tend to work on ideas that few beside them realize are good
" the intersection is the sweet spot for startups
this concept is a simple one and yet seeing it as a venn diagram is illuminating
it reminds you that there is an intersectionthat there are good ideas that seem bad
it also reminds you that the vast majority of ideas that seem bad are bad
the fact that the best ideas seem like bad ideas makes it even harder to recognize the big winners
one could have described microsoft and apple in exactly the same terms
harder still
wait, it gets worse
when you pick a big winner, you won't know it for two years
meanwhile, the one thing you can measure is dangerously misleading
but we know that's the wrong metric
except an inverse one
that's the scary thing: fundraising is not merely a useless metric, but positively misleading
the big winners could generate 10,000x returns
it takes a conscious effort not to do that too
but those are the wrong eyes to look through
we can afford to take at least 10x as much risk as demo day investors
and since risk is usually proportionate to reward, if you can afford to take more risk you should
i don't know what fraction of them currently raise more after demo day
[5] but the percentage is certainly way over 30%
and frankly the thought of a 30% success rate at fundraising makes my stomach clench
a demo day where only 30% of the startups were fundable would be a shambles
everyone would agree that yc had jumped the shark
we ourselves would feel that yc had jumped the shark
and yet we'd all be wrong
for better or worse that's never going to be more than a thought experiment
we could never stand it
i can make up all sorts of plausible justifications
it might dilute the value of the alumni network
i'm not a very good speaker
i say "um" a lot
sometimes i have to pause when i lose my train of thought
i wish i were a better speaker
but i don't wish i were a better speaker like i wish i were a better writer
having good ideas is most of writing well
i first noticed this at a conference several years ago
there was another speaker who was much better than me
he had all of us roaring with laughter
i seemed awkward and halting by comparison
afterward i put my talk online like i usually do
boy was he good
so i decided i'd pay close attention to what he said, to learn how he did it
after about ten sentences i found myself thinking "i don't want to be a good speaker
for example, when i give a talk i usually write it out beforehand
but here again there's a tradeoff between smoothness and ideas
all the time you spend practicing a talk, you could instead spend making it better
but i always end up spending most of the time rewriting it instead
every talk i give ends up being given from a manuscript full of things crossed out and rewritten
depending on your audience, there are even worse tradeoffs than these
that's true in writing too of course, but the descent is steeper with talks
any given person is dumber as a member of an audience than as a reader
every audience is an incipient mob, and a good speaker uses that
so are talks useless? they're certainly inferior to the written word as a source of ideas
but that's not all talks are good for
when i go to a talk, it's usually because i'm interested in the speaker
talks are also good at motivating me to do things
it's probably no coincidence that so many famous speakers are described as motivational speakers
that may be what public speaking is really for
it's probably what it was originally for
the emotional reactions you can elicit with a talk can be a powerful force
i wish i could say that force was more often used for good than ill, but i'm not sure
one of the cases he decided was brought by the owner of a food shop
the owner wanted the student to pay for the smells he was enjoying
the student was stealing his smells
it sounds ridiculous to us to treat smells as property
but i can imagine scenarios in which one could charge for smells
imagine we were living on a moon base where we had to buy air by the liter
i could imagine air suppliers adding scents at an extra charge
the reason it seems ridiculous to us to treat smells as property is that it wouldn't work to
it would work on a moon base, though
what counts as property depends on what works to treat as property
and that not only can change, but has changed
but hunter gatherers didn't treat land, for example, as property in the way we do
[2] but we are in the midst of such a change now
but with the arrival of networks, it's as if we've moved to a planet with a breathable atmosphere
data moves like smells now
but building new things takes too long
people should be able to charge for content when it works to charge for content
but by "works" i mean something more subtle than "when they can get away with it
" i mean when people can charge for content without warping society in order to do it
the crazy legal measures that the labels and studios have been taking have a lot of that flavor
newspapers and magazines are just as screwed, but they are at least declining gracefully
the riaa and mpaa would make us breathe through tubes if they could
ultimately it comes down to common sense
this is where it's helpful to have working democracies and multiple sovereign countries
private property is an extremely useful ideaarguably one of our greatest inventions
so far, each new definition of it has brought us increasing material wealth
[4] it seems reasonable to suppose the newest one will too
in this essay i'm going to demonstrate this phenomenon by describing some
any one of them could make you a billionaire
don't worry, it's not a sign of weakness
arguably it's a sign of sanity
the biggest startup ideas are terrifying
and not just because they'd be a lot of work
she says to him:
here's the thing: if you ever got me, you wouldn't have a clue what to do with me
that's what these ideas say to us
this phenomenon is one of the most important things you can understand about startups
[1] you'd expect big startup ideas to be attractive, but actually they tend to repel you
and that has a bunch of consequences
even the most ambitious people are probably best off approaching them obliquely
a new search engine
the best ideas are just on the right side of impossible
i don't know if this one is possible, but there are signs it might be
that was not a natural move for microsoft
they did it because they were afraid of google, and google was in the search business
microsoft : google :: google : facebook
google used to give me a page of the right answers, fast, with no clutter
and the pages don't have the clean, sparse feel they used to
google search results used to look like the output of a unix utility
now if i accidentally put the cursor in the wrong place, anything might happen
the way to win here is to build the search engine all the hackers use
and for the first time in over a decade the idea of switching seems thinkable to me
feel free to make it excessively hackerish
make it really good for code search, for example
replace email
email was not designed to be used the way we use it now
email is not a messaging protocol
it's a todo list
or rather, my inbox is a todo list, and email is the way things get onto it
but it is a disastrously bad todo list
as a todo list protocol, the new protocol should give more power to the recipient than email does
i want there to be more restrictions on what someone can put on my todo list
) when does it have to be done?
this is one of those ideas that's like an irresistible force meeting an immovable object
on one hand, entrenched protocols are impossible to replace
and if email is going to get replaced eventually, why not now?
they're all at the mercy of email too
whatever you build, make it fast
gmail has become painfully slow
gmail is slow because google can't afford to spend a lot on it
but people will pay for this
i'd have no problem paying $50 a month
at least $1000 a month
replace universities
people are all over this idea lately, and i think they're onto something
one could do a lot better for a lot less money
i don't think universities will disappear
they won't be replaced wholesale
they'll just lose the de facto monopoly on certain types of learning that they once had
y combinator itself is arguably one of them
if learning breaks up into many little pieces, credentialling may separate from it
universities seem the place to start
internet drama
hollywood has been slow to embrace the internet
a lot of the reason is the horribleness of cable clients, also known as tvs
our family didn't wait for apple tv
we hated our last tv so much that a few months ago we replaced it with an imac bolted to the wall
more can be stolen by things that are a little more closely related, like games
there are two ways delivery and payment could play out
if that's the way things play out, there will also be a need for such infrastructure companies
the next steve jobs
his answer was simply "no
" i already feared that would be the answer
i asked more to see how he'd qualify it
but he didn't qualify it at all
no, there will be no more great new stuff beyond whatever's currently in the pipeline
so if apple's not going to make the next ipad, who is? none of the existing players
so the company that creates the next wave of hardware is probably going to have to be a startup
i realize it sounds preposterously ambitious for a startup to try to become as big as apple
but no more ambitious than it was for apple to become as big as apple, and they did it
steve jobs has shown us what's possible
now steve is gone there's a vacuum we can all feel
if a new company led boldly into the future of hardware, users would follow
the ceo of that company, the "next steve jobs," might not measure up to steve jobs
but he wouldn't have to
he'd just have to do a better job than samsung and hp and nokia, and that seems pretty doable
bring back moore's law
the last 10 years have reminded us what moore's law actually says
actually what it says is that circuit densities will double every 18 months
it used to seem pedantic to point that out
not any more
intel can no longer give us faster cpus, just more of them
this moore's law is not as good as the old one
there are several ways to approach this problem
and if it's not impossible but simply very hard, it might be worth trying to write it
the expected value would be high even if the chance of succeeding was low
the reason the expected value is so high is web services
and that would in turn mean that you got practically all the users
they'd take most of intel's business
then the programmer still does much of the work of optimization
these people might be your employees, or you might create a marketplace for optimization
i realize how crazy all this sounds
in fact, what i like about this idea is all the different ways in which it's wrong
trying to write the sufficiently smart compiler is by definition a mistake
now that's what i call a startup idea
ongoing diagnosis
for example, in 2004 bill clinton found he was feeling short of breath
it seems reasonable to assume bill clinton has the best medical care available
ditto for cancer
cancer will show up on some sort of radar screen immediately
(of course, what shows up on the radar screen may be different from what we think of now as cancer
for example, a friend of mine once had her brain scanned as part of a study
she was horrified when the doctors running the study discovered what appeared to be a large tumor
after further testing, it turned out to be a harmless cyst
but it cost her a few days of terror
but i think that's just an artifact of current limitations
there is room for a lot of startups here
let me conclude with some tactical advice
don't say, for example, that you're going to replace email
if you do that you raise too many expectations
just say you're building todo-list software
that sounds harmless
people can notice you've replaced email when it's a fait accompli
empirically, the way to do really big things seems to be to start with deceptively small things
empirically, it's not just for other people that you need to start small
you need to for your own sake
neither bill gates nor mark zuckerberg knew at first how big their companies were going to get
all they knew was that they were onto something
you'll be better off if you operate like columbus and just head in a general westerly direction
start with something you know works, and when you expand, expand westward
it felt as if there was some kind of wall between us
i could never quite tell if they understood what i was saying
you won't have to babysit the round to make sure it happens
was there some kind of inverse relation between resourcefulness and being hard to talk to?
you don't have to explain in detail; they'll chase down all the implications
that's the connection
it's conversational resourcefulness
they traversed idea space as gingerly as a very old person traverses the physical world
the unsuccessful founders weren't stupid
they just weren't eager to
so being hard to talk to was not what was killing the unsuccessful startups
it was a sign of an underlying lack of resourcefulness
that's what was killing them
but the most immediate evidence i had that something was amiss was that i couldn't talk to them
there are great startup ideas lying around unexploited right under our noses
one reason we don't see them is a phenomenon i call schlep blindness
schlep was originally a yiddish word but has passed into general use in the us
it means a tedious, unpleasant task
no one likes schleps, but hackers especially dislike them
maybe that's possible, but i haven't seen it
one of the many things we do at y combinator is teach hackers about the inevitability of schleps
no, you can't start a startup by just writing code
i remember going through this realization myself
a company is defined by the schleps it will undertake
and schleps should be dealt with the same way you'd deal with a cold swimming pool: just jump in
the most dangerous thing about our dislike of schleps is that much of it is unconscious
your unconscious won't even let you see ideas that involve painful schleps
that's schlep blindness
the phenomenon isn't limited to startups
their unconscious mind decides for them, shrinking from the work involved
the most striking example i know of schlep blindness is stripe, or rather stripe's idea
thousands of people must have known about this problem
you'd have to make deals with banks
plus there are probably all sorts of regulations to comply with
it's a lot more intimidating to start a startup like this than a recipe site
that scariness makes ambitious ideas doubly valuable
(this is also true of starting a startup generally
maybe that's one reason the most successful startups of all so often have young founders
in practice the founders grow with the problems
but no one seems able to foresee that, not even older, more experienced founders
they don't know how much they can grow, but they also don't know how much they'll need to
older founders only make the first mistake
ignorance can't solve everything though
some ideas so obviously entail alarming schleps that anyone can see them
how do you see ideas like that? the trick i recommend is to take yourself out of the picture
somehow it's as if most places were sprayed with startupicide
i wondered about this for years
a couple weeks ago i finally figured it out
i was framing the question wrong
the problem is not that most towns kill startups
it's that death is the default for startups, and most towns don't save them
startups in other places are just doing what startups naturally do: fail
the real question is, what's saving startups in places like silicon valley? [2]
environment
and what drives them both is the number of startup people around you
it's quite a leap to start a startup
it's an unusual thing to do
but in silicon valley it seems normal
in most places, if you start a startup, people treat you as if you're unemployed
having people around you care about what you're doing is an extraordinarily powerful force
even the most willful people are susceptible to it
he responded so eagerly that for about half a second i found myself considering doing it
in most other cities, the prospect of starting a startup just doesn't seem real
in the valley it's not only real but fashionable
that no doubt causes a lot of people to start startups who shouldn't
but i think that's ok
the second component of the antidote is chance meetings with people who can help you
the reason startups are more likely to make it here is that great things happen to them too
in the valley, lightning has a sign bit
and moreover has advanced views, for 2004, on founders retaining control of their companies
you can't say precisely what the miracle will be, or even for sure that one will happen
i bet this is true even for startups we fund
chance meetings play a role like the role relaxation plays in having ideas
the critical thing in both cases is that they drift just the right amount
the meeting between larry page and sergey brin was a good example
for larry page the most important component of the antidote was sergey brin, and vice versa
the antidote is people
i'm not sure why this is so
a large part of yc's function is to accelerate that process
to make a startup hub, you need a lot of people interested in startups
there are three reasons
the first, obviously, is that if you don't have enough density, the chance meetings don't happen
sean parker was exactly what facebook needed in 2004
this is one of the reasons we fund such a large number of companies, incidentally
in most places the atmosphere pulls you back toward the mean
i flew into the bay area a few days ago
i notice this every time i fly over the valley: somehow you can sense something is going on
obviously you can sense prosperity in how well kept a place looks
but there are different kinds of prosperity
silicon valley doesn't look like boston, or new york, or la, or dc
</textarea>
</div>
<div id="prepro_status"></div>
<div class="hh">Controls/Options:</div>
<button id="learn" class="abutton">learn/restart</button>
<button id="resume" class="abutton">resume</button>
<button id="stop" class="abutton">pause</button>
<!-- <button id="gradcheck">gradcheck</button> -->
<textarea id="newnet" style="width:100%; height:200px;">
// model parameters
generator = 'lstm'; // can be 'rnn' or 'lstm'
hidden_sizes = [20,20]; // list of sizes of hidden layers
letter_size = 5; // size of letter embeddings
// optimization
regc = 0.000001; // L2 regularization strength
learning_rate = 0.01; // learning rate
clipval = 5.0; // clip gradients at this value
</textarea><br />
protip: if your perplexity is exploding with Infinity try lowering the initial learning rate
<br>
<div id="status">
<div>
<div class="hh">Training stats:</div>
<div class="aslider">
<div class="slider_header">Learning rate: you want to anneal this over time if you're training for longer time.</div>
<div class="theslider" id="lr_slider"></div>
<div class="slider_value" id="lr_text"></div>
</div>
<canvas id="pplgraph"></canvas>
<div id="ticktime"></div>
<div id="gradclip"></div>
<div id="epoch"></div>
<div id="ppl"></div>
<div style="clear:both;"></div>
</div>
<div class="hh">Model samples:</div>
<div id="controls">
<div class="aslider">
<div class="slider_header">Softmax sample temperature: lower setting will generate more likely predictions, but you'll see more of the same common words again and again. Higher setting will generate less frequent words but you might see more spelling errors.</div>
<div class="theslider" id="temperature_slider"></div>
<div class="slider_value" id="temperature_text"></div>
</div>
</div>
<div id="samples"></div>
<div class="hh">Greedy argmax prediction:</div>
<div id="argmax"></div>
</div>
<div id="io">
<div class="hh">I/O save/load model JSON</div>
<button id="savemodel" class="abutton">save model</button>
<button id="loadmodel" class="abutton">load model</button>
<div>
You can save or load models with JSON using the textarea below.
</div>
<textarea style="width:100%; height:200px;" id="tio"></textarea>
<br>
<div class="hh">Pretrained model:</div>
You can also choose to load an example pretrained model with the button below to see what the predictions look like in later stages. The pretrained model is an LSTM with one layer of 100 units, trained for ~10 hours. After clicking button below you should see the perplexity plummet to about 3.0, and see the predictions become better.<br>
<button id="loadpretrained" class="abutton">load pretrained</button>
</div>
</div>
</body>
</html>
|
