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Zappa–Szép product

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323:
showed that any non-regular transitive permutation group with a regular subgroup is a Zappa–Szép product of the regular subgroup and a point stabilizer. He gives PSL(2,11) and the alternating group of degree 5 as examples, and of course every alternating group of prime degree is an example. This
1420: 1491: 324:
same paper gives a number of examples of groups which cannot be realized as Zappa–Szép products of proper subgroups, such as the quaternion group and the alternating group of degree 6.
1572: 1846: 1511: 1273: 1691: 1660: 316:-subgroup, and in fact that the group is a (multiple factor) Zappa–Szép product of a certain set of representatives of its Sylow subgroups. 86:(1950) although it was independently studied by others including B.H. Neumann (1935), G.A. Miller (1935), and J.A. de Séguier (1904). 332:
As with the direct and semidirect products, there is an external version of the Zappa–Szép product for groups which are not known
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Szép, J. (1950), "On the structure of groups which can be represented as the product of two subgroups",
1831:
Zappa, G. (1940), "Sulla costruzione dei gruppi prodotto di due dati sottogruppi permutabili traloro",
1870: 1757: 1736: 222: 212: 320: 63: 1925: 1907: 1886: 1860: 1726: 75: 1840: 1785: 1705: 1687: 1656: 1175: 1020: 417: 216: 1917: 1878: 1819: 1775: 1765: 238: 99: 1701: 1748:
Miller, G. A. (1935), "Groups which are the products of two permutable proper subgroups",
1697: 1683: 1675: 1239: 256: 83: 1874: 1761: 1740: 1780: 1648: 1496: 242: 226: 1810:
Takeuchi, M. (1981), "Matched pairs of groups and bismash products of Hopf algebras",
1940: 305: 301: 279: 1929: 1890: 35: 17: 1415:{\displaystyle (h_{1}k_{1})(h_{2}k_{2})=(h_{1}k_{1}h_{2}k_{1}^{-1})(k_{1}k_{2})} 995:
denote each group's identity element) and suppose there exist mappings α :
297: 259: 79: 31: 1882: 1823: 864:
More concisely, the first three properties above assert the mapping α :
727: 1789: 1921: 1770: 1709: 1717:
Michor, P. W. (1989), "Knit products of graded Lie algebras and groups",
308:. This shows that every soluble group is a Zappa–Szép product of a Hall 263: 67: 1912: 1865: 1731: 1156: 1030:, define a multiplication and an inversion mapping by, respectively, 1719:
Proceedings of the Winter School on Geometry and Physics, Srni
293:
of upper triangular matrices with positive diagonal entries.
1721:, Suppl. Rendiconti Circolo Matematico di Palermo, Ser. II, 1855:
Agore, A.L.; Chirvasitu, A.; Ion, B.; Militaru, G. (2007),
1246:, then the mappings α and β are given by, respectively, α( 845:. This establishes injectivity, and for surjectivity, use 175:
If either (and hence both) of these statements hold, then
336:
to be subgroups of a given group. To motivate this, let
1519: 1499: 1428: 1276: 1566: 1505: 1485: 1414: 1898:Brin, M. G. (2005). "On the Zappa-Szép Product". 1653:Regular Subgroups of Primitive Permutation Groups 444:which turn out to have the following properties: 1750:Proceedings of the National Academy of Sciences 1226:be an internal Zappa–Szép product of subgroups 1194:is, in fact, an internal Zappa–Szép product of 344:be an internal Zappa–Szép product of subgroups 1486:{\displaystyle h_{1}k_{1}h_{2}k_{1}^{-1}\in H} 296:One of the most important examples of this is 8: 1851:; Edizioni Cremonense, Rome, (1942) 119–125. 1655:. American Mathematical Soc. pp. 1–2. 117:. The following statements are equivalent: 1845:: CS1 maint: location missing publisher ( 1214:Relation to semidirect and direct products 928:, then the last two properties amount to ( 1911: 1864: 1779: 1769: 1730: 1567:{\displaystyle k_{1}h_{2}k_{1}^{-1}\in H} 1549: 1544: 1534: 1524: 1518: 1498: 1468: 1463: 1453: 1443: 1433: 1427: 1403: 1393: 1374: 1369: 1359: 1349: 1339: 1320: 1310: 1294: 1284: 1275: 1857:Factorization problems for finite groups 1019:satisfying the properties above. On the 1640: 1838: 1651:; Cheryl E. Praeger; Jan Saxl (2010). 1833:Atti Secondo Congresso Un. Mat. Ital. 1578:is an internal semidirect product of 7: 300:'s 1937 theorem on the existence of 241:asserts that there exists a unique 912:. If we denote the left action by 25: 1613:is an internal direct product of 70:. It is a generalization of the 1682:(in German), Berlin, New York: 1143:is a group called the external 278:is a Zappa–Szép product of the 1409: 1386: 1383: 1332: 1326: 1303: 1300: 1277: 1270:. This is easy to see because 702:. From these, it follows that 1: 983:Turning this around, suppose 62:) describes a way in which a 328:External Zappa–Szép products 90:Internal Zappa–Szép products 66:can be constructed from two 908:on (the underlying set of) 884:on (the underlying set of) 1963: 179:is said to be an internal 1900:Communications in Algebra 1883:10.1007/s10468-009-9145-6 1824:10.1080/00927878108822621 1630:Complement (group theory) 920:and the right action by 151:, there exists a unique 44:Zappa–Rédei–Szép product 250:upper triangular matrix 1798:Acta Sci. Math. Szeged 1568: 1507: 1493:since by normality of 1487: 1416: 312:-subgroup and a Sylow 289:) and the group (say) 1922:10.1081/AGB-200047404 1771:10.1073/pnas.21.7.469 1569: 1508: 1488: 1417: 78:. It is named after 1517: 1497: 1426: 1274: 1186:, respectively, and 991:are groups (and let 757:) is a bijection of 262:entries on the main 213:general linear group 1875:2007math......3471A 1762:1935PNAS...21..469M 1741:1992math......4220M 1557: 1476: 1382: 765:(Indeed, suppose α( 76:semidirect products 56:exact factorization 42:(also known as the 27:Mathematics concept 1564: 1540: 1503: 1483: 1459: 1412: 1365: 1145:Zappa–Szép product 888:and that β : 229:. For each matrix 181:Zappa–Szép product 40:Zappa–Szép product 18:Zappa-Szep product 1693:978-3-540-03825-2 1662:978-0-8218-4654-4 1649:Martin W. Liebeck 1589:If, in addition, 1506:{\displaystyle H} 1021:cartesian product 60:bicrossed product 16:(Redirected from 1954: 1933: 1915: 1893: 1868: 1850: 1844: 1836: 1826: 1805: 1792: 1783: 1773: 1743: 1734: 1712: 1680:Endliche Gruppen 1667: 1666: 1645: 1609:. In this case, 1574:. In this case, 1573: 1571: 1570: 1565: 1556: 1548: 1539: 1538: 1529: 1528: 1512: 1510: 1509: 1504: 1492: 1490: 1489: 1484: 1475: 1467: 1458: 1457: 1448: 1447: 1438: 1437: 1421: 1419: 1418: 1413: 1408: 1407: 1398: 1397: 1381: 1373: 1364: 1363: 1354: 1353: 1344: 1343: 1325: 1324: 1315: 1314: 1299: 1298: 1289: 1288: 416:). This defines 372:, there exist α( 239:QR decomposition 113:be subgroups of 100:identity element 98:be a group with 21: 1962: 1961: 1957: 1956: 1955: 1953: 1952: 1951: 1937: 1936: 1897: 1854: 1837: 1830: 1809: 1795: 1747: 1716: 1694: 1684:Springer-Verlag 1674: 1671: 1670: 1663: 1647: 1646: 1642: 1637: 1627: 1530: 1520: 1515: 1514: 1495: 1494: 1449: 1439: 1429: 1424: 1423: 1399: 1389: 1355: 1345: 1335: 1316: 1306: 1290: 1280: 1272: 1271: 1216: 1103: 1096: 1089: 1082: 1075: 1068: 1061: 1054: 1047: 1040: 979: 973: 966: 960: 953: 947: 940: 934: 844: 837: 822: 807: 793: 786: 775: 697: 690: 679: 672: 657: 646: 639: 628: 622: 612: 605: 594: 583: 577: 563: 556: 545: 539: 521: 514: 503: 497: 330: 227:complex numbers 197: 92: 48:general product 28: 23: 22: 15: 12: 11: 5: 1960: 1958: 1950: 1949: 1939: 1938: 1935: 1934: 1906:(2): 393–424. 1895: 1852: 1828: 1818:(8): 841–882, 1807: 1793: 1756:(7): 469–472, 1745: 1714: 1713:, Kap. VI, §4. 1692: 1669: 1668: 1661: 1639: 1638: 1636: 1633: 1626: 1623: 1563: 1560: 1555: 1552: 1547: 1543: 1537: 1533: 1527: 1523: 1502: 1482: 1479: 1474: 1471: 1466: 1462: 1456: 1452: 1446: 1442: 1436: 1432: 1411: 1406: 1402: 1396: 1392: 1388: 1385: 1380: 1377: 1372: 1368: 1362: 1358: 1352: 1348: 1342: 1338: 1334: 1331: 1328: 1323: 1319: 1313: 1309: 1305: 1302: 1297: 1293: 1287: 1283: 1279: 1215: 1212: 1174:are subgroups 1147:of the groups 1133: 1132: 1105: 1101: 1094: 1087: 1080: 1073: 1066: 1059: 1052: 1045: 1038: 977: 971: 964: 958: 951: 945: 938: 932: 842: 835: 820: 805: 791: 784: 773: 763: 762: 745:, the mapping 735: 714:, the mapping 695: 688: 677: 670: 664: 663: 655: 644: 637: 626: 620: 614: 610: 603: 592: 581: 575: 565: 561: 554: 543: 537: 527: 519: 512: 501: 495: 489: 329: 326: 306:soluble groups 243:unitary matrix 196: 193: 173: 172: 141: 91: 88: 26: 24: 14: 13: 10: 9: 6: 4: 3: 2: 1959: 1948: 1945: 1944: 1942: 1931: 1927: 1923: 1919: 1914: 1909: 1905: 1901: 1896: 1892: 1888: 1884: 1880: 1876: 1872: 1867: 1862: 1858: 1853: 1848: 1842: 1834: 1829: 1825: 1821: 1817: 1813: 1812:Comm. Algebra 1808: 1803: 1799: 1794: 1791: 1787: 1782: 1777: 1772: 1767: 1763: 1759: 1755: 1751: 1746: 1742: 1738: 1733: 1728: 1724: 1720: 1715: 1711: 1707: 1703: 1699: 1695: 1689: 1685: 1681: 1677: 1673: 1672: 1664: 1658: 1654: 1650: 1644: 1641: 1634: 1632: 1631: 1624: 1622: 1620: 1616: 1612: 1608: 1604: 1600: 1596: 1593:is normal in 1592: 1587: 1585: 1581: 1577: 1561: 1558: 1553: 1550: 1545: 1541: 1535: 1531: 1525: 1521: 1500: 1480: 1477: 1472: 1469: 1464: 1460: 1454: 1450: 1444: 1440: 1434: 1430: 1404: 1400: 1394: 1390: 1378: 1375: 1370: 1366: 1360: 1356: 1350: 1346: 1340: 1336: 1329: 1321: 1317: 1311: 1307: 1295: 1291: 1285: 1281: 1269: 1265: 1261: 1257: 1253: 1249: 1245: 1241: 1237: 1233: 1229: 1225: 1221: 1213: 1211: 1209: 1205: 1201: 1197: 1193: 1189: 1185: 1181: 1177: 1173: 1169: 1165: 1161: 1158: 1154: 1150: 1146: 1142: 1138: 1130: 1126: 1122: 1118: 1114: 1110: 1106: 1100: 1093: 1086: 1079: 1072: 1065: 1058: 1051: 1044: 1037: 1033: 1032: 1031: 1029: 1025: 1022: 1018: 1014: 1010: 1007:and β : 1006: 1002: 998: 994: 990: 986: 981: 976: 970: 963: 957: 950: 944: 937: 931: 927: 923: 919: 915: 911: 907: 903: 899: 895: 891: 887: 883: 879: 875: 871: 867: 862: 860: 856: 852: 848: 841: 834: 830: 826: 819: 815: 811: 804: 800: 797: 790: 783: 779: 772: 768: 760: 756: 752: 748: 744: 740: 736: 733: 729: 725: 721: 717: 713: 709: 705: 704: 703: 701: 694: 687: 683: 676: 669: 661: 654: 650: 643: 636: 632: 625: 619: 615: 609: 602: 598: 591: 587: 580: 574: 570: 566: 560: 553: 549: 542: 536: 532: 528: 525: 518: 511: 507: 500: 494: 490: 487: 483: 479: 475: 471: 467: 463: 459: 455: 451: 447: 446: 445: 443: 439: 435: 432:and β : 431: 427: 423: 419: 415: 411: 407: 403: 399: 395: 391: 387: 383: 379: 375: 371: 367: 363: 359: 355: 352:of the group 351: 347: 343: 339: 335: 327: 325: 322: 321:George Miller 317: 315: 311: 307: 303: 302:Sylow systems 299: 294: 292: 288: 284: 281: 280:unitary group 277: 273: 269: 265: 261: 258: 254: 251: 248:and a unique 247: 244: 240: 236: 232: 228: 224: 221: 218: 214: 210: 206: 202: 194: 192: 190: 186: 182: 178: 170: 166: 162: 159:and a unique 158: 154: 150: 146: 142: 139: 135: 131: 127: 123: 120: 119: 118: 116: 112: 108: 104: 101: 97: 89: 87: 85: 81: 77: 73: 69: 65: 61: 57: 53: 49: 45: 41: 37: 34:, especially 33: 19: 1947:Group theory 1913:math/0406044 1903: 1899: 1866:math/0703471 1856: 1832: 1815: 1811: 1801: 1797: 1753: 1749: 1732:math/9204220 1722: 1718: 1679: 1652: 1643: 1628: 1618: 1614: 1610: 1606: 1602: 1598: 1594: 1590: 1588: 1583: 1579: 1575: 1267: 1263: 1259: 1255: 1251: 1247: 1243: 1235: 1231: 1227: 1223: 1219: 1217: 1207: 1203: 1199: 1195: 1191: 1187: 1183: 1179: 1171: 1167: 1163: 1159: 1152: 1148: 1144: 1140: 1136: 1134: 1128: 1124: 1120: 1116: 1112: 1108: 1098: 1091: 1084: 1077: 1070: 1063: 1056: 1049: 1042: 1035: 1027: 1023: 1016: 1012: 1008: 1004: 1000: 996: 992: 988: 984: 982: 974: 968: 961: 955: 948: 942: 935: 929: 925: 921: 917: 913: 909: 905: 902:right action 897: 893: 889: 885: 881: 873: 869: 865: 863: 858: 854: 850: 846: 839: 832: 828: 824: 817: 813: 809: 802: 798: 795: 788: 781: 777: 770: 766: 764: 758: 754: 750: 746: 742: 738: 731: 723: 719: 715: 711: 707: 699: 692: 685: 681: 674: 667: 665: 659: 652: 648: 641: 634: 630: 623: 617: 607: 600: 596: 595:) α(β( 589: 585: 578: 572: 568: 558: 551: 547: 540: 534: 530: 523: 516: 509: 505: 498: 492: 485: 481: 477: 473: 469: 465: 461: 457: 453: 449: 441: 437: 433: 429: 425: 421: 413: 409: 405: 401: 397: 393: 389: 385: 381: 377: 373: 369: 365: 361: 357: 353: 349: 345: 341: 337: 333: 331: 318: 313: 309: 295: 290: 286: 282: 275: 271: 267: 252: 245: 234: 230: 219: 208: 204: 200: 198: 188: 184: 180: 176: 174: 168: 164: 160: 156: 152: 148: 144: 137: 133: 129: 125: 121: 114: 110: 106: 102: 95: 93: 59: 55: 52:knit product 51: 47: 43: 39: 36:group theory 29: 1725:: 171–175, 1676:Huppert, B. 878:left action 651:)) β( 356:. For each 298:Philip Hall 82:(1940) and 80:Guido Zappa 32:mathematics 1635:References 1176:isomorphic 396:such that 266:such that 217:invertible 167:such that 105:, and let 1835:, Bologna 1597:, then α( 1559:∈ 1551:− 1478:∈ 1470:− 1376:− 1069: α( 1048:) ( 737:For each 728:bijection 706:For each 420:α : 364:and each 319:In 1935, 225:over the 143:For each 84:Jenő Szép 68:subgroups 1941:Category 1930:15169734 1891:18024087 1841:citation 1790:16588002 1678:(1967), 1625:See also 1127:,  1119:,  1097:)  1090:,  1076:,  857:,  831:,  816:,  787:). Then 666:for all 658:,  647:,  599:,  588:,  546:) = β(β( 522:,  472:for all 418:mappings 334:a priori 264:diagonal 257:positive 223:matrices 195:Examples 1871:Bibcode 1804:: 57–61 1781:1076628 1758:Bibcode 1737:Bibcode 1702:0224703 1202:} and { 1166:} and { 1157:subsets 1115:) = (α( 823:)) = α( 726:) is a 274:. Thus 211:), the 1928:  1889:  1788:  1778:  1710:527050 1708:  1700:  1690:  1659:  1258:and β( 1240:normal 1155:. The 808:) = α( 776:) = α( 633:) = β( 584:) = α( 508:) = α( 460:and β( 384:and β( 237:, the 169:g = hk 72:direct 38:, the 1926:S2CID 1908:arXiv 1887:S2CID 1861:arXiv 1727:arXiv 1422:and 1256:k h k 1234:. If 1135:Then 1123:), β( 1083:), β( 1062:) = ( 954:and ( 900:is a 876:is a 861:)).) 838:)) = 392:) in 380:) in 255:with 220:n × n 203:= GL( 64:group 1847:link 1786:PMID 1706:OCLC 1688:ISBN 1657:ISBN 1617:and 1605:) = 1582:and 1266:) = 1254:) = 1230:and 1218:Let 1206:} × 1182:and 1170:} × 1151:and 987:and 967:) = 941:) = 853:, α( 849:= α( 827:, α( 812:, α( 794:= α( 749:↦ β( 718:↦ α( 640:, α( 515:, α( 480:and 468:) = 456:) = 408:) β( 400:= α( 348:and 304:for 260:real 199:Let 187:and 128:and 109:and 94:Let 74:and 1918:doi 1879:doi 1820:doi 1776:PMC 1766:doi 1242:in 1238:is 1198:× { 1178:to 1162:× { 904:of 880:of 741:in 730:of 710:in 698:in 680:in 606:), 557:), 484:in 476:in 368:in 360:in 233:in 215:of 183:of 163:in 155:in 147:in 136:= { 58:or 30:In 1943:: 1924:. 1916:. 1904:33 1902:. 1885:, 1877:, 1869:, 1859:, 1843:}} 1839:{{ 1814:, 1802:12 1800:, 1784:, 1774:, 1764:, 1754:21 1752:, 1735:, 1723:22 1704:, 1698:MR 1696:, 1686:, 1621:. 1586:. 1513:, 1262:, 1224:HK 1222:= 1210:. 1190:× 1139:× 1131:)) 1111:, 1055:, 1041:, 1026:× 1015:→ 1011:× 1003:→ 999:× 980:. 924:→ 916:→ 896:→ 892:× 872:→ 868:× 801:, 780:, 769:, 753:, 722:, 691:, 684:, 673:, 629:, 616:β( 571:, 567:α( 550:, 533:, 529:β( 526:)) 504:, 491:α( 464:, 452:, 448:α( 440:→ 436:× 428:→ 424:× 412:, 404:, 398:kh 388:, 376:, 342:HK 340:= 310:p' 272:QR 270:= 191:. 132:∩ 126:HK 124:= 54:, 50:, 46:, 1932:. 1920:: 1910:: 1894:. 1881:: 1873:: 1863:: 1849:) 1827:. 1822:: 1816:9 1806:. 1768:: 1760:: 1744:. 1739:: 1729:: 1665:. 1619:K 1615:H 1611:G 1607:h 1603:h 1601:, 1599:k 1595:G 1591:K 1584:K 1580:H 1576:G 1562:H 1554:1 1546:1 1542:k 1536:2 1532:h 1526:1 1522:k 1501:H 1481:H 1473:1 1465:1 1461:k 1455:2 1451:h 1445:1 1441:k 1435:1 1431:h 1410:) 1405:2 1401:k 1395:1 1391:k 1387:( 1384:) 1379:1 1371:1 1367:k 1361:2 1357:h 1351:1 1347:k 1341:1 1337:h 1333:( 1330:= 1327:) 1322:2 1318:k 1312:2 1308:h 1304:( 1301:) 1296:1 1292:k 1286:1 1282:h 1278:( 1268:k 1264:h 1260:k 1252:h 1250:, 1248:k 1244:G 1236:H 1232:K 1228:H 1220:G 1208:K 1204:e 1200:e 1196:H 1192:K 1188:H 1184:K 1180:H 1172:K 1168:e 1164:e 1160:H 1153:K 1149:H 1141:K 1137:H 1129:h 1125:k 1121:h 1117:k 1113:k 1109:h 1107:( 1104:) 1102:2 1099:k 1095:2 1092:h 1088:1 1085:k 1081:2 1078:h 1074:1 1071:k 1067:1 1064:h 1060:2 1057:k 1053:2 1050:h 1046:1 1043:k 1039:1 1036:h 1034:( 1028:K 1024:H 1017:K 1013:H 1009:K 1005:H 1001:H 997:K 993:e 989:K 985:H 978:2 975:k 972:1 969:k 965:2 962:k 959:1 956:k 952:2 949:h 946:1 943:h 939:2 936:h 933:1 930:h 926:k 922:k 918:h 914:h 910:K 906:H 898:K 894:H 890:K 886:H 882:K 874:H 870:H 866:K 859:h 855:k 851:k 847:h 843:2 840:h 836:2 833:h 829:k 825:k 821:1 818:h 814:k 810:k 806:1 803:h 799:k 796:k 792:1 789:h 785:2 782:h 778:k 774:1 771:h 767:k 761:. 759:K 755:h 751:k 747:k 743:H 739:h 734:. 732:H 724:h 720:k 716:h 712:K 708:k 700:K 696:2 693:k 689:1 686:k 682:H 678:2 675:h 671:1 668:h 662:) 660:h 656:2 653:k 649:h 645:2 642:k 638:1 635:k 631:h 627:2 624:k 621:1 618:k 613:) 611:2 608:h 604:1 601:h 597:k 593:1 590:h 586:k 582:2 579:h 576:1 573:h 569:k 564:) 562:2 559:h 555:1 552:h 548:k 544:2 541:h 538:1 535:h 531:k 524:h 520:2 517:k 513:1 510:k 506:h 502:2 499:k 496:1 493:k 488:. 486:K 482:k 478:H 474:h 470:k 466:e 462:k 458:h 454:h 450:e 442:K 438:H 434:K 430:H 426:H 422:K 414:h 410:k 406:h 402:k 394:K 390:h 386:k 382:H 378:h 374:k 370:H 366:h 362:K 358:k 354:G 350:K 346:H 338:G 314:p 291:K 287:n 285:( 283:U 276:G 268:A 253:R 246:Q 235:G 231:A 209:C 207:, 205:n 201:G 189:K 185:H 177:G 171:. 165:K 161:k 157:H 153:h 149:G 145:g 140:} 138:e 134:K 130:H 122:G 115:G 111:K 107:H 103:e 96:G 20:)

Index

Zappa-Szep product
mathematics
group theory
group
subgroups
direct
semidirect products
Guido Zappa
Jenő Szép
identity element
general linear group
invertible
matrices
complex numbers
QR decomposition
unitary matrix
upper triangular matrix
positive
real
diagonal
unitary group
Philip Hall
Sylow systems
soluble groups
George Miller
mappings
bijection
left action
right action
cartesian product

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