Knowledge

Erdős–Kac theorem

Source 📝

1488: 427: 929: 1074: 265: 1498:
A hollow sphere the size of the planet Earth filled with fine sand would have around 10 grains. A volume the size of the observable universe would have around 10 grains of sand. There might be room for 10 quantum strings in such a universe.
714: 574: 773: 141: 1613: 1251: 1286:
For example, 1,000,000,003 = 23 × 307 × 141623. The following table provides a numerical summary of the growth of the average number of distinct prime factors of a natural number
761: 940: 241: 422:{\displaystyle \lim _{x\rightarrow \infty }\left({\frac {1}{x}}\cdot \#\left\{n\leq x:a\leq {\frac {\omega (n)-\log \log n}{\sqrt {\log \log n}}}\leq b\right\}\right)=\Phi (a,b)} 465: 177: 1550: 1148: 594: 1523: 1324: 1304: 473: 924:{\displaystyle \lim _{x\rightarrow \infty }\left({\frac {1}{x}}\cdot \#\left\{n\leq x:a\leq {\frac {f(n)-A(n)}{B(n)}}\leq b\right\}\right)=\Phi (a,b)} 184: 1563: 1495:
Around 12.6% of 10,000 digit numbers are constructed from 10 distinct prime numbers and around 68% are constructed from between 7 and 13 primes.
192: 1812: 1735: 76: 1156: 1673: 1727: 1505:
It is very difficult if not impossible to discover the Erdős-Kac theorem empirically, as the Gaussian only shows up when
1807: 188: 47: 1283:
The Erdős–Kac theorem means that the construction of a number around one billion requires on average three primes.
1069:{\displaystyle A(n)=\sum _{p\leq n}{\frac {f(p)}{p}},\qquad B(n)={\sqrt {\sum _{p\leq n}{\frac {f(p)^{2}}{p}}}}.} 719: 67: 1718:
Kuo, Wentang; Liu, Yu-Ru (2008). "The Erdős–Kac theorem and its generalizations". In De Koninck, Jean-Marie;
210: 1802: 1560:
showed that the best possible uniform asymptotic bound on the error in the approximation to a Gaussian is
1265: 1502:
Numbers of this magnitude—with 186 digits—would require on average only 6 primes for construction.
1261: 147: 1698: 1553: 435: 153: 1770: 1731: 1690: 1528: 588: 1741: 1719: 1706: 1682: 1647: 1671:(1940). "The Gaussian Law of Errors in the Theory of Additive Number Theoretic Functions". 1126: 709:{\displaystyle \scriptstyle f(p_{1}^{a_{1}}\cdots p_{k}^{a_{k}})=f(p_{1})+\cdots +f(p_{k})} 1745: 1710: 1557: 1787: 1508: 1491:
A spreading Gaussian distribution of distinct primes illustrating the Erdos-Kac theorem
1309: 1289: 1773: 1796: 1664: 39: 31: 1724:
Anatomy of integers. Based on the CRM workshop, Montreal, Canada, March 13--17, 2006
1632: 1268:
guarantees that after appropriate rescaling, the above expression will be Gaussian.
1092:
is approximately normally distributed with mean and variance log log 
1272: 569:{\displaystyle \Phi (a,b)={\frac {1}{\sqrt {2\pi }}}\int _{a}^{b}e^{-t^{2}/2}\,dt.} 59: 1088:
is a randomly chosen large integer, then the number of distinct prime factors of
17: 1788:
Timothy Gowers: The Importance of Mathematics (part 6, 4 mins in) and (part 7)
1694: 1778: 1256:
This sum counts how many distinct prime factors our random natural number
1668: 1651: 43: 1702: 136:{\displaystyle {\frac {\omega (n)-\log \log n}{\sqrt {\log \log n}}}} 1686: 1487: 1755:
Statistical Independence in Probability, Analysis and Number Theory
1726:. CRM Proceedings and Lecture Notes. Vol. 46. Providence, RI: 1486: 1608:{\displaystyle O\left({\frac {1}{\sqrt {\log \log n}}}\right).} 1246:{\displaystyle I_{n_{2}}+I_{n_{3}}+I_{n_{5}}+I_{n_{7}}+\ldots } 1096:. This comes from the fact that given a random natural number 1150:, consider the following sum of indicator random variables: 180: 1084:
Intuitively, Kac's heuristic for the result says that if
467:
is the normal (or "Gaussian") distribution, defined as
723: 598: 1566: 1531: 1511: 1312: 1292: 1159: 1129: 943: 776: 722: 597: 476: 438: 268: 213: 156: 79: 1271:
The actual proof of the theorem, due to Erdős, uses
1328: 1607: 1544: 1517: 1318: 1298: 1245: 1142: 1068: 923: 755: 708: 568: 459: 421: 235: 171: 135: 27:Fundamental theorem of probabilistic number theory 1260:has. It can be shown that this sum satisfies the 778: 270: 46:, and also known as the fundamental theorem of 8: 1574: 1565: 1536: 1530: 1510: 1311: 1291: 1229: 1224: 1209: 1204: 1189: 1184: 1169: 1164: 1158: 1134: 1128: 1049: 1033: 1021: 1015: 975: 963: 942: 837: 798: 781: 775: 756:{\displaystyle \scriptstyle |f(p)|\leq 1} 741: 724: 721: 696: 668: 644: 639: 634: 619: 614: 609: 596: 556: 546: 540: 532: 522: 517: 498: 475: 437: 329: 290: 273: 267: 214: 212: 155: 80: 78: 1623: 1275:to make rigorous the above intuition. 236:{\displaystyle {\sqrt {\log \log n}}} 7: 1115:Now, denoting the event "the number 1388:1,000,000,000,000,000,000,000,000 1079: 903: 811: 788: 477: 439: 401: 303: 280: 25: 1674:American Journal of Mathematics 1266:Lindeberg central limit theorem 999: 187:.) This is an extension of the 1046: 1039: 1009: 1003: 987: 981: 953: 947: 918: 906: 878: 872: 864: 858: 849: 843: 785: 742: 738: 732: 725: 702: 689: 674: 661: 652: 602: 492: 480: 454: 442: 416: 404: 341: 335: 277: 166: 160: 92: 86: 66:, then, loosely speaking, the 1: 1728:American Mathematical Society 1631:Rényi, A.; Turán, P. (1958). 207:with a typical error of size 1813:Theorems about prime numbers 1525:starts getting to be around 58:) is the number of distinct 1757:. John Wiley and Sons, Inc. 1633:"On a theorem of Erdös-Kac" 1104:is divisible by some prime 48:probabilistic number theory 1829: 1112:are mutually independent. 460:{\displaystyle \Phi (a,b)} 172:{\displaystyle \omega (n)} 1100:, the events "the number 1722:; Luca, Florian (eds.). 1545:{\displaystyle 10^{100}} 1080:Kac's original heuristic 191:, which states that the 68:probability distribution 203:) is log log  189:Hardy–Ramanujan theorem 1609: 1546: 1519: 1492: 1320: 1300: 1247: 1144: 1070: 925: 757: 710: 570: 461: 423: 237: 173: 137: 1610: 1547: 1520: 1490: 1321: 1301: 1248: 1145: 1143:{\displaystyle n_{p}} 1071: 926: 758: 711: 571: 462: 424: 238: 174: 138: 1730:. pp. 209–216. 1652:10.4064/aa-4-1-71-84 1564: 1529: 1509: 1310: 1290: 1264:, and therefore the 1157: 1127: 941: 774: 720: 595: 474: 436: 266: 211: 154: 77: 1808:Normal distribution 1774:"Erdős–Kac Theorem" 1348:of distinct primes 1262:Lindeberg condition 651: 626: 579:More generally, if 527: 148:normal distribution 1771:Weisstein, Eric W. 1753:Kac, Mark (1959). 1605: 1552:. More precisely, 1542: 1515: 1493: 1316: 1296: 1279:Numerical examples 1243: 1140: 1066: 1032: 974: 921: 792: 753: 752: 706: 705: 630: 605: 566: 513: 457: 419: 284: 233: 169: 133: 1737:978-0-8218-4406-9 1720:Granville, Andrew 1596: 1595: 1518:{\displaystyle n} 1485: 1484: 1319:{\displaystyle n} 1299:{\displaystyle n} 1061: 1059: 1017: 994: 959: 882: 806: 777: 589:additive function 511: 510: 380: 379: 298: 269: 247:Precise statement 231: 131: 130: 50:, states that if 36:Erdős–Kac theorem 18:Erdős-Kac theorem 16:(Redirected from 1820: 1784: 1783: 1758: 1749: 1714: 1681:(1/4): 738–742. 1656: 1655: 1640:Acta Arithmetica 1637: 1628: 1614: 1612: 1611: 1606: 1601: 1597: 1579: 1575: 1551: 1549: 1548: 1543: 1541: 1540: 1524: 1522: 1521: 1516: 1329: 1325: 1323: 1322: 1317: 1306:with increasing 1305: 1303: 1302: 1297: 1252: 1250: 1249: 1244: 1236: 1235: 1234: 1233: 1216: 1215: 1214: 1213: 1196: 1195: 1194: 1193: 1176: 1175: 1174: 1173: 1149: 1147: 1146: 1141: 1139: 1138: 1119:is divisible by 1075: 1073: 1072: 1067: 1062: 1060: 1055: 1054: 1053: 1034: 1031: 1016: 995: 990: 976: 973: 930: 928: 927: 922: 899: 895: 894: 890: 883: 881: 867: 838: 807: 799: 791: 762: 760: 759: 754: 745: 728: 715: 713: 712: 707: 701: 700: 673: 672: 650: 649: 648: 638: 625: 624: 623: 613: 587:) is a strongly 575: 573: 572: 567: 555: 554: 550: 545: 544: 526: 521: 512: 503: 499: 466: 464: 463: 458: 428: 426: 425: 420: 397: 393: 392: 388: 381: 363: 362: 330: 299: 291: 283: 255: <  242: 240: 239: 234: 232: 215: 178: 176: 175: 170: 146:is the standard 142: 140: 139: 134: 132: 114: 113: 81: 21: 1828: 1827: 1823: 1822: 1821: 1819: 1818: 1817: 1793: 1792: 1769: 1768: 1765: 1752: 1738: 1717: 1687:10.2307/2371483 1663: 1660: 1659: 1635: 1630: 1629: 1625: 1620: 1570: 1562: 1561: 1532: 1527: 1526: 1507: 1506: 1346:Average number 1308: 1307: 1288: 1287: 1281: 1225: 1220: 1205: 1200: 1185: 1180: 1165: 1160: 1155: 1154: 1130: 1125: 1124: 1082: 1045: 1035: 977: 939: 938: 868: 839: 818: 814: 797: 793: 772: 771: 718: 717: 692: 664: 640: 615: 593: 592: 536: 528: 472: 471: 434: 433: 331: 310: 306: 289: 285: 264: 263: 249: 209: 208: 152: 151: 82: 75: 74: 28: 23: 22: 15: 12: 11: 5: 1826: 1824: 1816: 1815: 1810: 1805: 1795: 1794: 1791: 1790: 1785: 1764: 1763:External links 1761: 1760: 1759: 1750: 1736: 1715: 1658: 1657: 1622: 1621: 1619: 1616: 1604: 1600: 1594: 1591: 1588: 1585: 1582: 1578: 1573: 1569: 1539: 1535: 1514: 1483: 1482: 1479: 1476: 1473: 1469: 1468: 1465: 1462: 1459: 1455: 1454: 1451: 1448: 1445: 1441: 1440: 1437: 1434: 1431: 1427: 1426: 1423: 1420: 1417: 1413: 1412: 1409: 1406: 1403: 1399: 1398: 1395: 1392: 1389: 1385: 1384: 1381: 1378: 1375: 1374:1,000,000,000 1371: 1370: 1367: 1364: 1361: 1357: 1356: 1350: 1344: 1335: 1315: 1295: 1280: 1277: 1254: 1253: 1242: 1239: 1232: 1228: 1223: 1219: 1212: 1208: 1203: 1199: 1192: 1188: 1183: 1179: 1172: 1168: 1163: 1137: 1133: 1081: 1078: 1077: 1076: 1065: 1058: 1052: 1048: 1044: 1041: 1038: 1030: 1027: 1024: 1020: 1014: 1011: 1008: 1005: 1002: 998: 993: 989: 986: 983: 980: 972: 969: 966: 962: 958: 955: 952: 949: 946: 932: 931: 920: 917: 914: 911: 908: 905: 902: 898: 893: 889: 886: 880: 877: 874: 871: 866: 863: 860: 857: 854: 851: 848: 845: 842: 836: 833: 830: 827: 824: 821: 817: 813: 810: 805: 802: 796: 790: 787: 784: 780: 763:for all prime 751: 748: 744: 740: 737: 734: 731: 727: 704: 699: 695: 691: 688: 685: 682: 679: 676: 671: 667: 663: 660: 657: 654: 647: 643: 637: 633: 629: 622: 618: 612: 608: 604: 601: 577: 576: 565: 562: 559: 553: 549: 543: 539: 535: 531: 525: 520: 516: 509: 506: 502: 497: 494: 491: 488: 485: 482: 479: 456: 453: 450: 447: 444: 441: 430: 429: 418: 415: 412: 409: 406: 403: 400: 396: 391: 387: 384: 378: 375: 372: 369: 366: 361: 358: 355: 352: 349: 346: 343: 340: 337: 334: 328: 325: 322: 319: 316: 313: 309: 305: 302: 297: 294: 288: 282: 279: 276: 272: 251:For any fixed 248: 245: 230: 227: 224: 221: 218: 168: 165: 162: 159: 144: 143: 129: 126: 123: 120: 117: 112: 109: 106: 103: 100: 97: 94: 91: 88: 85: 38:, named after 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 1825: 1814: 1811: 1809: 1806: 1804: 1801: 1800: 1798: 1789: 1786: 1781: 1780: 1775: 1772: 1767: 1766: 1762: 1756: 1751: 1747: 1743: 1739: 1733: 1729: 1725: 1721: 1716: 1712: 1708: 1704: 1700: 1696: 1692: 1688: 1684: 1680: 1676: 1675: 1670: 1666: 1662: 1661: 1653: 1649: 1645: 1641: 1634: 1627: 1624: 1617: 1615: 1602: 1598: 1592: 1589: 1586: 1583: 1580: 1576: 1571: 1567: 1559: 1555: 1537: 1533: 1512: 1503: 1500: 1496: 1489: 1480: 1477: 1474: 1471: 1470: 1466: 1463: 1460: 1457: 1456: 1452: 1449: 1446: 1443: 1442: 1438: 1435: 1432: 1429: 1428: 1424: 1421: 1418: 1415: 1414: 1410: 1407: 1404: 1401: 1400: 1396: 1393: 1390: 1387: 1386: 1382: 1379: 1376: 1373: 1372: 1368: 1365: 1362: 1359: 1358: 1355: 1351: 1349: 1345: 1343: 1342: 1336: 1334: 1331: 1330: 1327: 1313: 1293: 1284: 1278: 1276: 1274: 1269: 1267: 1263: 1259: 1240: 1237: 1230: 1226: 1221: 1217: 1210: 1206: 1201: 1197: 1190: 1186: 1181: 1177: 1170: 1166: 1161: 1153: 1152: 1151: 1135: 1131: 1122: 1118: 1113: 1111: 1107: 1103: 1099: 1095: 1091: 1087: 1063: 1056: 1050: 1042: 1036: 1028: 1025: 1022: 1018: 1012: 1006: 1000: 996: 991: 984: 978: 970: 967: 964: 960: 956: 950: 944: 937: 936: 935: 915: 912: 909: 900: 896: 891: 887: 884: 875: 869: 861: 855: 852: 846: 840: 834: 831: 828: 825: 822: 819: 815: 808: 803: 800: 794: 782: 770: 769: 768: 766: 749: 746: 735: 729: 697: 693: 686: 683: 680: 677: 669: 665: 658: 655: 645: 641: 635: 631: 627: 620: 616: 610: 606: 599: 590: 586: 582: 563: 560: 557: 551: 547: 541: 537: 533: 529: 523: 518: 514: 507: 504: 500: 495: 489: 486: 483: 470: 469: 468: 451: 448: 445: 413: 410: 407: 398: 394: 389: 385: 382: 376: 373: 370: 367: 364: 359: 356: 353: 350: 347: 344: 338: 332: 326: 323: 320: 317: 314: 311: 307: 300: 295: 292: 286: 274: 262: 261: 260: 258: 254: 246: 244: 228: 225: 222: 219: 216: 206: 202: 198: 194: 190: 186: 182: 163: 157: 149: 127: 124: 121: 118: 115: 110: 107: 104: 101: 98: 95: 89: 83: 73: 72: 71: 69: 65: 61: 60:prime factors 57: 53: 49: 45: 41: 37: 33: 32:number theory 19: 1777: 1754: 1723: 1678: 1672: 1646:(1): 71–84. 1643: 1639: 1626: 1504: 1501: 1497: 1494: 1433:210,704,569 1353: 1347: 1340: 1338: 1332: 1285: 1282: 1273:sieve theory 1270: 1257: 1255: 1120: 1116: 1114: 1109: 1108:" for each 1105: 1101: 1097: 1093: 1089: 1085: 1083: 933: 764: 584: 580: 578: 431: 256: 252: 250: 204: 200: 196: 193:normal order 179:is sequence 145: 63: 55: 51: 35: 29: 1665:Erdős, Paul 1803:Paul Erdős 1797:Categories 1746:1187.11024 1711:0024.10203 1618:References 1354:deviation 1339:digits in 1337:Number of 40:Paul Erdős 1779:MathWorld 1695:0002-9327 1669:Kac, Mark 1590:⁡ 1584:⁡ 1352:Standard 1241:… 1026:≤ 1019:∑ 968:≤ 961:∑ 904:Φ 885:≤ 853:− 835:≤ 823:≤ 812:# 809:⋅ 789:∞ 786:→ 747:≤ 681:⋯ 628:⋯ 534:− 515:∫ 508:π 478:Φ 440:Φ 402:Φ 383:≤ 374:⁡ 368:⁡ 357:⁡ 351:⁡ 345:− 333:ω 327:≤ 315:≤ 304:# 301:⋅ 281:∞ 278:→ 226:⁡ 220:⁡ 158:ω 125:⁡ 119:⁡ 108:⁡ 102:⁡ 96:− 84:ω 44:Mark Kac 1703:2371483 1475:10 + 1 1461:10 + 1 1447:10 + 1 767:, then 716:) with 183:in the 181:A001221 1744:  1734:  1709:  1701:  1693:  1419:9,567 1360:1,000 432:where 34:, the 1699:JSTOR 1636:(PDF) 1558:Turán 1554:Rényi 1481:31.6 1478:1000 1123:" by 934:with 1732:ISBN 1691:ISSN 1556:and 1464:100 1453:7.1 1439:4.5 1425:3.2 1411:2.2 1383:1.7 1369:1.4 185:OEIS 42:and 1742:Zbl 1707:Zbl 1683:doi 1648:doi 1587:log 1581:log 1538:100 1472:10 1467:10 1458:10 1450:50 1444:10 1436:20 1430:10 1422:10 1416:10 1405:66 1402:10 1391:25 1377:10 779:lim 371:log 365:log 354:log 348:log 271:lim 223:log 217:log 195:of 150:. ( 122:log 116:log 105:log 99:log 70:of 62:of 30:In 1799:: 1776:. 1740:. 1705:. 1697:. 1689:. 1679:62 1677:. 1667:; 1642:. 1638:. 1534:10 1408:5 1397:2 1394:4 1380:3 1366:2 1363:4 1326:. 259:, 243:. 1782:. 1748:. 1713:. 1685:: 1654:. 1650:: 1644:4 1603:. 1599:) 1593:n 1577:1 1572:( 1568:O 1513:n 1341:n 1333:n 1314:n 1294:n 1258:n 1238:+ 1231:7 1227:n 1222:I 1218:+ 1211:5 1207:n 1202:I 1198:+ 1191:3 1187:n 1182:I 1178:+ 1171:2 1167:n 1162:I 1136:p 1132:n 1121:p 1117:n 1110:p 1106:p 1102:n 1098:n 1094:n 1090:n 1086:n 1064:. 1057:p 1051:2 1047:) 1043:p 1040:( 1037:f 1029:n 1023:p 1013:= 1010:) 1007:n 1004:( 1001:B 997:, 992:p 988:) 985:p 982:( 979:f 971:n 965:p 957:= 954:) 951:n 948:( 945:A 919:) 916:b 913:, 910:a 907:( 901:= 897:) 892:} 888:b 879:) 876:n 873:( 870:B 865:) 862:n 859:( 856:A 850:) 847:n 844:( 841:f 832:a 829:: 826:x 820:n 816:{ 804:x 801:1 795:( 783:x 765:p 750:1 743:| 739:) 736:p 733:( 730:f 726:| 703:) 698:k 694:p 690:( 687:f 684:+ 678:+ 675:) 670:1 666:p 662:( 659:f 656:= 653:) 646:k 642:a 636:k 632:p 621:1 617:a 611:1 607:p 603:( 600:f 591:( 585:n 583:( 581:f 564:. 561:t 558:d 552:2 548:/ 542:2 538:t 530:e 524:b 519:a 505:2 501:1 496:= 493:) 490:b 487:, 484:a 481:( 455:) 452:b 449:, 446:a 443:( 417:) 414:b 411:, 408:a 405:( 399:= 395:) 390:} 386:b 377:n 360:n 342:) 339:n 336:( 324:a 321:: 318:x 312:n 308:{ 296:x 293:1 287:( 275:x 257:b 253:a 229:n 205:n 201:n 199:( 197:ω 167:) 164:n 161:( 128:n 111:n 93:) 90:n 87:( 64:n 56:n 54:( 52:ω 20:)

Index

Erdős-Kac theorem
number theory
Paul Erdős
Mark Kac
probabilistic number theory
prime factors
probability distribution
normal distribution
A001221
OEIS
Hardy–Ramanujan theorem
normal order
additive function
Lindeberg condition
Lindeberg central limit theorem
sieve theory

Rényi
Turán
"On a theorem of Erdös-Kac"
doi
10.4064/aa-4-1-71-84
Erdős, Paul
Kac, Mark
American Journal of Mathematics
doi
10.2307/2371483
ISSN
0002-9327
JSTOR

Text is available under the Creative Commons Attribution-ShareAlike License. Additional terms may apply.