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Axiom of power set

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The power set axiom does not specify what subsets of a set exist, only that there is a set containing all those that do. Not all conceivable subsets are guaranteed to exist. In particular, the power set of an infinite set would contain only "constructible sets" if the universe is the
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The axiom of power set appears in most axiomatizations of set theory. It is generally considered uncontroversial, although
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The existence of the Cartesian product can be proved without using the power set axiom, as in the case of the
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and is not used in the formal language of the Zermelo–Fraenkel axioms. Rather, the subset relation
92: 1740: 1735: 1520: 1475: 987: 1092:{\displaystyle X_{1}\times \cdots \times X_{n}=(X_{1}\times \cdots \times X_{n-1})\times X_{n}.} 327: 299: 1597: 1434: 1426: 1397: 1367: 1298: 1230: 1215: 1200: 1199:. Princeton, NJ: D. Van Nostrand Company, 1960. Reprinted by Springer-Verlag, New York, 1974. 1167: 554: 504: 321: 1885: 1875: 1860: 1855: 1723: 1377: 317: 1754: 1692: 1510: 1330: 369: 351: 1136: 1890: 1687: 1668: 1572: 1557: 1514: 1450: 1392: 580: 560: 533: 345: 223: 199: 142: 1910: 1895: 1865: 1697: 1611: 1606: 285: 1119:
but in other models of ZF set theory could contain sets that are not constructible.
1845: 1840: 1658: 1587: 1545: 1404: 1308: 795: 112: 900:{\displaystyle (x,y)=\{\{x\},\{x,y\}\}\in {\mathcal {P}}({\mathcal {P}}(X\cup Y))} 1870: 1505: 1192: 124: 17: 1850: 1718: 1621: 1284: 1243: 984: 1653: 1616: 1567: 1465: 518: 501: 193: 973:{\displaystyle X\times Y\subseteq {\mathcal {P}}({\mathcal {P}}(X\cup Y)).} 1678: 1500: 217: 1550: 1317: 1257: 1242:
This article incorporates material from Axiom of power set on
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Set Theory: The Third Millennium Edition, Revised and Expanded
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of the Zermelo–Fraenkel axioms, the axiom of power set reads:
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The power set axiom allows a simple definition of the
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Berlin: Springer-Verlag. pp. 56–57. 1276: 1262: 1254: 419: 415: 1080: 1058: 1039: 1023: 1004: 998: 943: 942: 933: 932: 918: 873: 872: 863: 862: 806: 760: 759: 727: 688: 605: 582: 562: 426: 402: 395: 388: 380: 353: 329: 301: 252: 251: 249: 225: 201: 167: 166: 164: 144: 96:The elements of the power set of the set 80:Learn how and when to remove this message 91: 43:This article includes a list of general 1128: 7: 420: 396: 389: 382: 49:it lacks sufficient corresponding 25: 270:{\displaystyle {\mathcal {P}}(x)} 185:{\displaystyle {\mathcal {P}}(x)} 1307: 34: 27:Concept in axiomatic set theory 1246:, which is licensed under the 1070: 1032: 964: 961: 949: 939: 894: 891: 879: 869: 820: 808: 778: 766: 714:{\displaystyle x,y\in X\cup Y} 634: 622: 454: 451: 439: 427: 416: 403: 264: 258: 216:, consisting precisely of the 179: 173: 139:. It guarantees for every set 1: 1933: 1767:von Neumann–Bernays–Gödel 1207:(Springer-Verlag edition). 337:{\displaystyle \subseteq } 309:{\displaystyle \subseteq } 1568:One-to-one correspondence 1305: 1104:Kripke–Platek set theory 796:Kuratowski ordered pair 497:In English, this says: 344:is defined in terms of 282:constructive set theory 242:axiom of extensionality 159:the existence of a set 133:Zermelo–Fraenkel axioms 64:more precise citations. 1526:Constructible universe 1353:Constructibility (V=L) 1225:Kunen, Kenneth, 1980. 1160:Devlin, Keith (1984). 1117:constructible universe 1093: 974: 901: 785: 715: 671: 591: 571: 540:is also an element of 461: 362: 338: 310: 271: 234: 210: 186: 153: 120: 1749:Principia Mathematica 1583:Transfinite induction 1442:(i.e. set difference) 1094: 990:of sets recursively: 975: 902: 786: 716: 672: 592: 572: 462: 368:. Given this, in the 363: 339: 311: 272: 235: 211: 187: 154: 95: 1917:Axioms of set theory 1823:Burali-Forti paradox 1578:Set-builder notation 1531:Continuum hypothesis 1471:Symmetric difference 1210:Jech, Thomas, 2003. 997: 917: 805: 726: 687: 604: 581: 561: 474:is the power set of 379: 361:{\displaystyle \in } 352: 328: 300: 296:The subset relation 248: 224: 200: 163: 143: 137:axiomatic set theory 1784:Tarski–Grothendieck 1373:Limitation of size 1141:www.britannica.com 1089: 970: 897: 781: 711: 667: 587: 567: 482:is any element of 457: 358: 334: 306: 267: 230: 206: 182: 149: 129:axiom of power set 121: 1904: 1903: 1813:Russell's paradox 1762:Zermelo–Fraenkel 1663:Dedekind-infinite 1536:Diagonal argument 1435:Cartesian product 1299:Set (mathematics) 590:{\displaystyle Y} 570:{\displaystyle X} 555:Cartesian product 536:every element of 490:is any member of 322:formal set theory 233:{\displaystyle x} 209:{\displaystyle x} 152:{\displaystyle x} 90: 89: 82: 16:(Redirected from 1924: 1886:Bertrand Russell 1876:John von Neumann 1861:Abraham Fraenkel 1856:Richard Dedekind 1818:Suslin's problem 1729:Cantor's theorem 1446:De Morgan's laws 1311: 1278: 1271: 1264: 1255: 1197:Naive set theory 1185: 1184: 1182: 1180: 1163:Constructibility 1157: 1151: 1150: 1148: 1147: 1133: 1098: 1096: 1095: 1090: 1085: 1084: 1069: 1068: 1044: 1043: 1028: 1027: 1009: 1008: 979: 977: 976: 971: 948: 947: 938: 937: 906: 904: 903: 898: 878: 877: 868: 867: 790: 788: 787: 782: 765: 764: 720: 718: 717: 712: 676: 674: 673: 668: 596: 594: 593: 588: 576: 574: 573: 568: 521:, given any set 466: 464: 463: 458: 367: 365: 364: 359: 343: 341: 340: 335: 318:primitive notion 315: 313: 312: 307: 292:Formal statement 276: 274: 273: 268: 257: 256: 239: 237: 236: 231: 215: 213: 212: 207: 191: 189: 188: 183: 172: 171: 158: 156: 155: 150: 115:with respect to 111: 85: 78: 74: 71: 65: 60:this article by 51:inline citations 38: 37: 30: 21: 1932: 1931: 1927: 1926: 1925: 1923: 1922: 1921: 1907: 1906: 1905: 1900: 1827: 1806: 1790: 1755:New Foundations 1702: 1592: 1511:Cardinal number 1494: 1480: 1421: 1312: 1303: 1287: 1282: 1189: 1188: 1178: 1176: 1174: 1159: 1158: 1154: 1145: 1143: 1135: 1134: 1130: 1125: 1112: 1076: 1054: 1035: 1019: 1000: 995: 994: 915: 914: 803: 802: 724: 723: 685: 684: 602: 601: 579: 578: 559: 558: 551: 529:is a member of 377: 376: 370:formal language 350: 349: 326: 325: 298: 297: 294: 246: 245: 222: 221: 198: 197: 161: 160: 141: 140: 97: 86: 75: 69: 66: 56:Please help to 55: 39: 35: 28: 23: 22: 18:Power set axiom 15: 12: 11: 5: 1930: 1928: 1920: 1919: 1909: 1908: 1902: 1901: 1899: 1898: 1893: 1891:Thoralf Skolem 1888: 1883: 1878: 1873: 1868: 1863: 1858: 1853: 1848: 1843: 1837: 1835: 1829: 1828: 1826: 1825: 1820: 1815: 1809: 1807: 1805: 1804: 1801: 1795: 1792: 1791: 1789: 1788: 1787: 1786: 1781: 1776: 1775: 1774: 1759: 1758: 1757: 1745: 1744: 1743: 1732: 1731: 1726: 1721: 1716: 1710: 1708: 1704: 1703: 1701: 1700: 1695: 1690: 1685: 1676: 1671: 1666: 1656: 1651: 1650: 1649: 1644: 1639: 1629: 1619: 1614: 1609: 1603: 1601: 1594: 1593: 1591: 1590: 1585: 1580: 1575: 1573:Ordinal number 1570: 1565: 1560: 1555: 1554: 1553: 1548: 1538: 1533: 1528: 1523: 1518: 1508: 1503: 1497: 1495: 1493: 1492: 1489: 1485: 1482: 1481: 1479: 1478: 1473: 1468: 1463: 1458: 1453: 1451:Disjoint union 1448: 1443: 1437: 1431: 1429: 1423: 1422: 1420: 1419: 1418: 1417: 1412: 1401: 1400: 1398:Martin's axiom 1395: 1390: 1385: 1380: 1375: 1370: 1365: 1363:Extensionality 1360: 1355: 1350: 1349: 1348: 1343: 1338: 1328: 1322: 1320: 1314: 1313: 1306: 1304: 1302: 1301: 1295: 1293: 1289: 1288: 1283: 1281: 1280: 1273: 1266: 1258: 1239: 1238: 1223: 1214:. Springer. 1208: 1187: 1186: 1172: 1152: 1127: 1126: 1124: 1121: 1111: 1108: 1100: 1099: 1088: 1083: 1079: 1075: 1072: 1067: 1064: 1061: 1057: 1053: 1050: 1047: 1042: 1038: 1034: 1031: 1026: 1022: 1018: 1015: 1012: 1007: 1003: 981: 980: 969: 966: 963: 960: 957: 954: 951: 946: 941: 936: 931: 928: 925: 922: 908: 907: 896: 893: 890: 887: 884: 881: 876: 871: 866: 861: 858: 855: 852: 849: 846: 843: 840: 837: 834: 831: 828: 825: 822: 819: 816: 813: 810: 792: 791: 780: 777: 774: 771: 768: 763: 758: 755: 752: 749: 746: 743: 740: 737: 734: 731: 721: 710: 707: 704: 701: 698: 695: 692: 678: 677: 666: 663: 660: 657: 654: 651: 648: 645: 642: 639: 636: 633: 630: 627: 624: 621: 618: 615: 612: 609: 586: 566: 550: 547: 546: 545: 534:if and only if 468: 467: 456: 453: 450: 447: 444: 441: 438: 435: 432: 429: 425: 422: 418: 414: 411: 408: 405: 401: 398: 394: 391: 387: 384: 357: 346:set membership 333: 305: 293: 290: 266: 263: 260: 255: 229: 205: 181: 178: 175: 170: 148: 131:is one of the 88: 87: 42: 40: 33: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 1929: 1918: 1915: 1914: 1912: 1897: 1896:Ernst Zermelo 1894: 1892: 1889: 1887: 1884: 1882: 1881:Willard Quine 1879: 1877: 1874: 1872: 1869: 1867: 1864: 1862: 1859: 1857: 1854: 1852: 1849: 1847: 1844: 1842: 1839: 1838: 1836: 1834: 1833:Set theorists 1830: 1824: 1821: 1819: 1816: 1814: 1811: 1810: 1808: 1802: 1800: 1797: 1796: 1793: 1785: 1782: 1780: 1779:Kripke–Platek 1777: 1773: 1770: 1769: 1768: 1765: 1764: 1763: 1760: 1756: 1753: 1752: 1751: 1750: 1746: 1742: 1739: 1738: 1737: 1734: 1733: 1730: 1727: 1725: 1722: 1720: 1717: 1715: 1712: 1711: 1709: 1705: 1699: 1696: 1694: 1691: 1689: 1686: 1684: 1682: 1677: 1675: 1672: 1670: 1667: 1664: 1660: 1657: 1655: 1652: 1648: 1645: 1643: 1640: 1638: 1635: 1634: 1633: 1630: 1627: 1623: 1620: 1618: 1615: 1613: 1610: 1608: 1605: 1604: 1602: 1599: 1595: 1589: 1586: 1584: 1581: 1579: 1576: 1574: 1571: 1569: 1566: 1564: 1561: 1559: 1556: 1552: 1549: 1547: 1544: 1543: 1542: 1539: 1537: 1534: 1532: 1529: 1527: 1524: 1522: 1519: 1516: 1512: 1509: 1507: 1504: 1502: 1499: 1498: 1496: 1490: 1487: 1486: 1483: 1477: 1474: 1472: 1469: 1467: 1464: 1462: 1459: 1457: 1454: 1452: 1449: 1447: 1444: 1441: 1438: 1436: 1433: 1432: 1430: 1428: 1424: 1416: 1415:specification 1413: 1411: 1408: 1407: 1406: 1403: 1402: 1399: 1396: 1394: 1391: 1389: 1386: 1384: 1381: 1379: 1376: 1374: 1371: 1369: 1366: 1364: 1361: 1359: 1356: 1354: 1351: 1347: 1344: 1342: 1339: 1337: 1334: 1333: 1332: 1329: 1327: 1324: 1323: 1321: 1319: 1315: 1310: 1300: 1297: 1296: 1294: 1290: 1286: 1279: 1274: 1272: 1267: 1265: 1260: 1259: 1256: 1252: 1251: 1249: 1245: 1236: 1235:0-444-86839-9 1232: 1229:. Elsevier. 1228: 1224: 1221: 1220:3-540-44085-2 1217: 1213: 1209: 1206: 1205:0-387-90092-6 1202: 1198: 1194: 1191: 1190: 1175: 1173:3-540-13258-9 1169: 1165: 1164: 1156: 1153: 1142: 1138: 1132: 1129: 1122: 1120: 1118: 1109: 1107: 1105: 1086: 1081: 1077: 1073: 1065: 1062: 1059: 1055: 1051: 1048: 1045: 1040: 1036: 1029: 1024: 1020: 1016: 1013: 1010: 1005: 1001: 993: 992: 991: 989: 986: 967: 958: 955: 952: 929: 926: 923: 920: 913: 912: 911: 888: 885: 882: 859: 850: 847: 844: 838: 832: 823: 817: 814: 811: 801: 800: 799: 797: 775: 772: 769: 756: 750: 747: 744: 738: 732: 722: 708: 705: 702: 699: 696: 693: 690: 683: 682: 681: 664: 658: 655: 652: 649: 646: 643: 640: 637: 631: 628: 625: 616: 613: 610: 607: 600: 599: 598: 584: 564: 556: 548: 543: 539: 535: 532: 528: 524: 520: 517: 513: 509: 506: 503: 500: 499: 498: 495: 493: 489: 485: 481: 477: 473: 448: 445: 442: 436: 433: 430: 423: 412: 409: 406: 399: 392: 385: 375: 374: 373: 371: 355: 347: 331: 323: 319: 303: 291: 289: 287: 286:predicativity 283: 278: 261: 243: 227: 219: 203: 195: 176: 146: 138: 134: 130: 126: 118: 114: 109: 105: 101: 94: 84: 81: 73: 63: 59: 53: 52: 46: 41: 32: 31: 19: 1846:Georg Cantor 1841:Paul Bernays 1772:Morse–Kelley 1747: 1680: 1679:Subset  1626:hereditarily 1588:Venn diagram 1546:ordered pair 1461:Intersection 1405:Axiom schema 1382: 1241: 1240: 1226: 1211: 1196: 1177:. Retrieved 1162: 1155: 1144:. Retrieved 1140: 1131: 1113: 1101: 982: 909: 793: 680:Notice that 679: 557:of two sets 552: 549:Consequences 541: 537: 530: 526: 522: 515: 507: 496: 491: 487: 483: 479: 475: 471: 469: 295: 279: 128: 122: 107: 103: 99: 76: 67: 48: 1871:Thomas Jech 1714:Alternative 1693:Uncountable 1647:Ultrafilter 1506:Cardinality 1410:replacement 1358:Determinacy 1193:Paul Halmos 1110:Limitations 525:, this set 277:is unique. 125:mathematics 62:introducing 1866:Kurt Gödel 1851:Paul Cohen 1688:Transitive 1456:Identities 1440:Complement 1427:Operations 1388:Regularity 1326:Adjunction 1285:Set theory 1244:PlanetMath 1146:2023-08-06 1123:References 988:collection 244:, the set 45:references 1799:Paradoxes 1719:Axiomatic 1698:Universal 1674:Singleton 1669:Recursive 1612:Countable 1607:Amorphous 1466:Power set 1383:Power set 1341:dependent 1336:countable 1179:8 January 1074:× 1063:− 1052:× 1049:⋯ 1046:× 1017:× 1014:⋯ 1011:× 956:∪ 930:⊆ 924:× 886:∪ 860:∈ 773:∪ 757:∈ 706:∪ 700:∈ 656:∈ 650:∧ 644:∈ 611:× 519:such that 502:Given any 446:∈ 440:⇒ 434:∈ 421:∀ 417:⟺ 410:∈ 397:∀ 390:∃ 383:∀ 356:∈ 332:⊆ 316:is not a 304:⊆ 240:. By the 194:power set 117:inclusion 1911:Category 1803:Problems 1707:Theories 1683:Superset 1659:Infinite 1488:Concepts 1368:Infinity 1292:Overview 512:there is 70:May 2020 1741:General 1736:Zermelo 1642:subbase 1624: ( 1563:Forcing 1541:Element 1513: ( 1491:Methods 1378:Pairing 218:subsets 113:ordered 58:improve 1632:Filter 1622:Finite 1558:Family 1501:Almost 1346:global 1331:Choice 1318:Axioms 1233:  1218:  1203:  1170:  985:finite 514:a set 470:where 192:, the 127:, the 47:, but 1724:Naive 1654:Fuzzy 1617:Empty 1600:types 1551:tuple 1521:Class 1515:large 1476:Union 1393:Union 1637:base 1231:ISBN 1216:ISBN 1201:ISBN 1181:2023 1168:ISBN 577:and 1598:Set 505:set 320:in 220:of 196:of 135:of 123:In 1913:: 1195:, 1139:. 1106:. 798:, 597:: 510:, 494:. 486:, 478:, 348:, 288:. 106:, 102:, 1681:· 1665:) 1661:( 1628:) 1517:) 1277:e 1270:t 1263:v 1250:. 1237:. 1222:. 1183:. 1149:. 1087:. 1082:n 1078:X 1071:) 1066:1 1060:n 1056:X 1041:1 1037:X 1033:( 1030:= 1025:n 1021:X 1006:1 1002:X 968:. 965:) 962:) 959:Y 953:X 950:( 945:P 940:( 935:P 927:Y 921:X 895:) 892:) 889:Y 883:X 880:( 875:P 870:( 865:P 857:} 854:} 851:y 848:, 845:x 842:{ 839:, 836:} 833:x 830:{ 827:{ 824:= 821:) 818:y 815:, 812:x 809:( 779:) 776:Y 770:X 767:( 762:P 754:} 751:y 748:, 745:x 742:{ 739:, 736:} 733:x 730:{ 709:Y 703:X 697:y 694:, 691:x 665:. 662:} 659:Y 653:y 647:X 641:x 638:: 635:) 632:y 629:, 626:x 623:( 620:{ 617:= 614:Y 608:X 585:Y 565:X 544:. 542:x 538:z 531:y 527:z 523:z 516:y 508:x 492:z 488:w 484:y 480:z 476:x 472:y 455:] 452:) 449:x 443:w 437:z 431:w 428:( 424:w 413:y 407:z 404:[ 400:z 393:y 386:x 265:) 262:x 259:( 254:P 228:x 204:x 180:) 177:x 174:( 169:P 147:x 119:. 110:} 108:z 104:y 100:x 98:{ 83:) 77:( 72:) 68:( 54:. 20:)

Index

Power set axiom
references
inline citations
improve
introducing
Learn how and when to remove this message

ordered
inclusion
mathematics
Zermelo–Fraenkel axioms
axiomatic set theory
power set
subsets
axiom of extensionality
constructive set theory
predicativity
primitive notion
formal set theory
set membership
formal language
Given any
set
there is
such that
if and only if
Cartesian product
Kuratowski ordered pair
finite
collection

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