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Semi-simplicity

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322:, which itself has an eigenvector, and thus by induction is diagonalizable. Conversely, diagonalizable operators are easily seen to be semi-simple, as invariant subspaces are direct sums of eigenspaces, and any eigenbasis for this subspace can be extended to an eigenbasis of the full space. 100:
of the base field does not divide the order of the group). So in the case of finite groups with this condition, every finite-dimensional representation is semi-simple. Especially in algebra and representation theory, "semi-simplicity" is also called
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of a group or a Lie algebra is semisimple, that is, whether every finite-dimensional representation decomposes as a direct sum of irreducible representations. The answer, in general, is no. For example, the representation of
1133: 1399: 851: 776: 896: 1224: 1170:. The presence of this so-called polarization causes the category of polarizable Hodge structures to be semi-simple. Another example from algebraic geometry is the category of 1002: 1725: 1701: 1613: 1585: 1561: 1328: 949:
is a collection of objects and maps between such objects, the idea being that the maps between the objects preserve some structure inherent in these objects. For example,
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objects, and simple objects are those that do not contain non-trivial proper sub-objects. The precise definitions of these words depends on the context.
1298: 106: 1703:. Thus, the just-mentioned result about representations of compact groups applies. It is also possible to prove semisimplicity of representations of 1068: 1898: 1336: 318:. This is because such an operator always has an eigenvector; if it is, in addition, semi-simple, then it has a complementary invariant 296: 1849: 1814: 1404:
is not a direct sum of irreducibles. (There is precisely one nontrivial invariant subspace, the span of the first basis element,
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is semi-simple if and only if it is the direct sum of simple modules (the trivial module is the empty direct sum). Finally,
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vector spaces are the simple ones. So it is a basic result of linear algebra that any finite-dimensional vector space is the
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says that any finite-dimensional representation of a finite group is a direct sum of simple representations (provided the
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Examples of semi-simple rings include fields and, more generally, finite direct products of fields. For a finite group
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As indicated above, the theory of semi-simple rings is much more easy than the one of general rings. For example, any
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is simply connected, there is a one-to-one correspondence between the finite-dimensional representations of
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in a semi-simple category is a product of matrix rings over division rings, i.e., semi-simple.
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of simple vector spaces; in other words, all finite-dimensional vector spaces are semi-simple.
1894: 1869: 1845: 1810: 1164: 1060: 672: 331: 212: 197: 132: 1949: 1939: 1616: 1056: 965: 631:{\displaystyle M_{n_{1}}(D_{1})\times M_{n_{2}}(D_{2})\times \cdots \times M_{n_{r}}(D_{r})} 404: 32: 1824: 1407: 1232: 641: 1953: 1820: 1731: 1588: 1522: 1502: 1458: 1178: 1159: 335: 263: 201: 173: 127: 40: 1912: 1662: 1642: 1622: 1478: 1434: 315: 189: 28: 16:
This article is about mathematical use. For the philosophical reduction thinking, see
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Nilpotence, radicaux et structures monoĂŻdales. With an appendix by Peter O'Sullivan
1844:. Graduate texts in mathematics. Vol. 131 (2 ed.). Springer. p. 27. 1153: 783: 270: 231: 63: 1944: 1563:
is a complex semisimple Lie algebra, every finite-dimensional representation of
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Bondarko, Mikhail V. (2012), "Weight structures and 'weights' on the hearts of
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is a linear algebraic group whose radical of the identity component is trivial.
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Many of the above notions of semi-simplicity are recovered by the concept of a
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or, equivalently, product) of finitely many simple objects. It follows from
1052: 1005: 116: 1257:, this category is semi-simple if and only if the equivalence relation is 2015:
Lie Groups, Lie Algebras, and Representations: An Elementary Introduction
1128:{\displaystyle \operatorname {End} _{C}(X)=\operatorname {Hom} _{C}(X,X)} 2017:, Graduate Texts in Mathematics, vol. 222 (2nd ed.), Springer 1394:{\displaystyle \Pi (x)={\begin{pmatrix}1&x\\0&1\end{pmatrix}}} 211:
These notions of semi-simplicity can be unified using the language of
1877: 411:-module. As it turns out, this is equivalent to requiring that any 1261:. This fact is a conceptual cornerstone in the theory of motives. 204:; if the field is algebraically closed, this is the same as being 2032: 1865:
More generally, the same definition of semi-simplicity works for
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is a sum of irreducibles. Weyl's original proof of this used the
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Semisimple abelian categories also arise from a combination of a
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is semi-simple if and only if the category of finitely generated
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is called semi-simple if there is a collection of simple objects
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directly by algebraic means, as in Section 10.3 of Hall's book.
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is semi-simple in the sense above if and only if the subalgebra
387:(the trivial module 0 is semi-simple, but not simple). For an 1747:
is a Lie algebra that is a direct sum of simple Lie algebras.
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if the only subrepresentations it contains are either {0} or
1809:(2nd ed.). Englewood Cliffs, N.J.: Prentice-Hall, Inc. 471:-modules, this fact is an important dichotomy, which causes 2033:
Are abelian non-degenerate tensor categories semisimple?
957:-linear maps between them form a category, for any ring 1876:. Rend. Sem. Mat. Univ. Padova 108 (2002), 107–291. 1163:, i.e., pure Hodge structures equipped with a suitable 495:| does not divide the characteristic, in particular if 192:), then the only simple matrices are of size 1-by-1. A 1360: 771:{\displaystyle F\subseteq \operatorname {End} _{F}(V)} 1709: 1685: 1665: 1645: 1625: 1597: 1569: 1545: 1525: 1505: 1481: 1461: 1437: 1410: 1339: 1314: 1235: 1193: 1071: 1018: 977: 862: 856:
of modules over a semi-simple ring must split, i.e.,
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is simple, if it has no submodules other than 0 and
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Motives, numerical equivalence, and semi-simplicity
1539:decomposes as a sum of irreducibles. Similarly, if 510:is semisimple if and only if it is (isomorphic to) 1802: 1719: 1695: 1671: 1651: 1631: 1607: 1579: 1555: 1531: 1511: 1487: 1467: 1443: 1423: 1393: 1322: 1241: 1218: 1127: 1031: 996: 890: 845: 770: 697: 657: 630: 153: 165:a finite-dimensional vector space) is said to be 1615:is the complexification of the Lie algebra of a 295:-invariant subspace. This is equivalent to the 1455:, then every finite-dimensional representation 1219:{\displaystyle \operatorname {Mot} (k)_{\sim }} 314:, semi-simplicity of a matrix is equivalent to 27:is a widespread concept in disciplines such as 1889:Peters, Chris A. M.; Steenbrink, Joseph H. M. 1780: 1778: 1305:category of finite-dimensional representations 778:generated by the powers (i.e., iterations) of 109:says a finite-dimensional representation of a 8: 51:is one that can be decomposed into a sum of 902:, this means that there are no non-trivial 1872:. See for example Yves AndrĂ©, Bruno Kahn: 499:is a field of characteristic zero. By the 1943: 1711: 1710: 1708: 1687: 1686: 1684: 1664: 1644: 1624: 1599: 1598: 1596: 1571: 1570: 1568: 1547: 1546: 1544: 1524: 1504: 1480: 1460: 1436: 1415: 1409: 1355: 1338: 1316: 1315: 1313: 1234: 1210: 1192: 1101: 1076: 1070: 1023: 1017: 982: 976: 861: 804: 750: 729: 680: 674: 649: 643: 619: 604: 599: 577: 562: 557: 541: 526: 521: 515: 491:to be more difficult than the case when | 134: 1283:Semi-simplicity in representation theory 846:{\displaystyle 0\to M'\to M\to M''\to 0} 1774: 1299:Weyl's theorem on complete reducibility 107:Weyl's theorem on complete reducibility 69:, then a nontrivial finite-dimensional 1841:A first course in noncommutative rings 226:Introductory example of vector spaces 7: 2001: 1989: 1977: 1965: 1916:, Invent. math. 107, 447~452 (1992) 1712: 1688: 1600: 1572: 1548: 891:{\displaystyle M\cong M'\oplus M''} 1878:https://arxiv.org/abs/math/0203273 1526: 1506: 1462: 1340: 14: 1801:(1971). "Semi-Simple operators". 455:. Since the theory of modules of 218:, and generalized to semi-simple 997:{\displaystyle X_{\alpha }\in C} 910:of integers is not semi-simple: 1720:{\displaystyle {\mathfrak {g}}} 1696:{\displaystyle {\mathfrak {g}}} 1608:{\displaystyle {\mathfrak {g}}} 1580:{\displaystyle {\mathfrak {g}}} 1556:{\displaystyle {\mathfrak {g}}} 1856:"(2.5) Theorem and Definition" 1349: 1343: 1207: 1200: 1122: 1110: 1091: 1085: 837: 826: 820: 809: 765: 759: 740: 734: 692: 686: 625: 612: 583: 570: 547: 534: 443:is semi-simple if and only if 145: 1: 1228:adequate equivalence relation 473:modular representation theory 326:Semi-simple modules and rings 202:direct sum of simple matrices 1323:{\displaystyle \mathbb {R} } 898:. From the point of view of 1945:10.4310/HHA.2012.v14.n1.a12 1032:{\displaystyle X_{\alpha }} 407:if it is semi-simple as an 90:irreducible representations 2091: 1752:semisimple algebraic group 1292: 1286: 383:-module direct summand of 329: 306:For vector spaces over an 15: 1763:Semisimple representation 1519:is unitary, showing that 1431:.) On the other hand, if 1289:Semisimple representation 1271:and a (suitably related) 914:is not the direct sum of 713:matrices with entries in 1734:(which are semisimple). 1303:One can ask whether the 1249:. As was conjectured by 1149:-modules is semisimple. 698:{\displaystyle M_{n}(D)} 501:Artin–Wedderburn theorem 269:on a finite-dimensional 154:{\displaystyle T:V\to V} 2013:Hall, Brian C. (2015), 1932:Homology Homotopy Appl. 1838:Lam, Tsit-Yuen (2001). 475:, i.e., the case when | 88:(these are also called 1891:Mixed Hodge structures 1745:semisimple Lie algebra 1721: 1697: 1673: 1653: 1633: 1609: 1581: 1557: 1533: 1513: 1499:with respect to which 1489: 1469: 1445: 1425: 1395: 1324: 1243: 1220: 1129: 1033: 998: 933:Semi-simple categories 892: 847: 772: 699: 659: 632: 155: 18:Reduction (philosophy) 2065:Representation theory 1722: 1698: 1674: 1654: 1634: 1610: 1582: 1558: 1534: 1514: 1490: 1470: 1446: 1426: 1424:{\displaystyle e_{1}} 1396: 1325: 1277:triangulated category 1259:numerical equivalence 1244: 1242:{\displaystyle \sim } 1221: 1130: 1034: 1004:, i.e., ones with no 999: 893: 848: 773: 700: 660: 658:{\displaystyle D_{i}} 633: 461:representation theory 330:Further information: 230:If one considers all 156: 103:complete reducibility 37:representation theory 1901:; see Corollary 2.12 1707: 1683: 1663: 1643: 1623: 1595: 1567: 1543: 1532:{\displaystyle \Pi } 1523: 1512:{\displaystyle \Pi } 1503: 1479: 1468:{\displaystyle \Pi } 1459: 1435: 1408: 1337: 1312: 1233: 1191: 1182:projective varieties 1069: 1016: 975: 860: 803: 795:short exact sequence 728: 673: 642: 514: 447:is semi-simple and | 308:algebraically closed 262:or, equivalently, a 254:Semi-simple matrices 186:algebraically closed 133: 2038:Semisimple category 1870:additive categories 1156:is the category of 900:homological algebra 782:inside the ring of 459:is the same as the 451:| is invertible in 303:being square-free. 2075:Algebraic geometry 1797:Hoffman, Kenneth; 1758:Semisimple algebra 1717: 1693: 1669: 1649: 1629: 1619:compact Lie group 1605: 1577: 1553: 1529: 1509: 1485: 1465: 1441: 1421: 1391: 1385: 1320: 1239: 1216: 1125: 1039:itself, such that 1029: 994: 888: 843: 768: 695: 655: 628: 413:finitely generated 297:minimal polynomial 286:invariant subspace 194:semi-simple matrix 184:. If the field is 151: 126:(in other words a 49:semi-simple object 45:algebraic geometry 1899:978-3-540-77015-2 1672:{\displaystyle K} 1652:{\displaystyle K} 1632:{\displaystyle K} 1488:{\displaystyle G} 1444:{\displaystyle G} 1295:Maschke's theorem 1165:positive definite 1158:polarizable pure 1141:Moreover, a ring 1061:endomorphism ring 432:asserts that the 430:Maschke's theorem 332:Semisimple module 316:diagonalizability 94:Maschke's theorem 2082: 2018: 2005: 1999: 1993: 1987: 1981: 1975: 1969: 1963: 1957: 1956: 1947: 1923: 1917: 1908: 1902: 1887: 1881: 1863: 1857: 1855: 1835: 1829: 1828: 1808: 1794: 1788: 1782: 1726: 1724: 1723: 1718: 1716: 1715: 1702: 1700: 1699: 1694: 1692: 1691: 1678: 1676: 1675: 1670: 1658: 1656: 1655: 1650: 1638: 1636: 1635: 1630: 1617:simply connected 1614: 1612: 1611: 1606: 1604: 1603: 1586: 1584: 1583: 1578: 1576: 1575: 1562: 1560: 1559: 1554: 1552: 1551: 1538: 1536: 1535: 1530: 1518: 1516: 1515: 1510: 1494: 1492: 1491: 1486: 1474: 1472: 1471: 1466: 1450: 1448: 1447: 1442: 1430: 1428: 1427: 1422: 1420: 1419: 1400: 1398: 1397: 1392: 1390: 1389: 1329: 1327: 1326: 1321: 1319: 1273:weight structure 1248: 1246: 1245: 1240: 1225: 1223: 1222: 1217: 1215: 1214: 1160:Hodge structures 1152:An example from 1134: 1132: 1131: 1126: 1106: 1105: 1081: 1080: 1038: 1036: 1035: 1030: 1028: 1027: 1003: 1001: 1000: 995: 987: 986: 966:abelian category 897: 895: 894: 889: 887: 876: 852: 850: 849: 844: 836: 819: 790:is semi-simple. 777: 775: 774: 769: 755: 754: 704: 702: 701: 696: 685: 684: 664: 662: 661: 656: 654: 653: 637: 635: 634: 629: 624: 623: 611: 610: 609: 608: 582: 581: 569: 568: 567: 566: 546: 545: 533: 532: 531: 530: 422:is semi-simple. 405:semi-simple ring 174:linear subspaces 160: 158: 157: 152: 58:For example, if 33:abstract algebra 23:In mathematics, 2090: 2089: 2085: 2084: 2083: 2081: 2080: 2079: 2050: 2049: 2025: 2012: 2009: 2008: 2000: 1996: 1988: 1984: 1976: 1972: 1964: 1960: 1925: 1924: 1920: 1909: 1905: 1888: 1884: 1864: 1860: 1852: 1837: 1836: 1832: 1817: 1796: 1795: 1791: 1783: 1776: 1771: 1740: 1732:Fusion category 1705: 1704: 1681: 1680: 1661: 1660: 1641: 1640: 1621: 1620: 1593: 1592: 1589:unitarian trick 1565: 1564: 1541: 1540: 1521: 1520: 1501: 1500: 1477: 1476: 1457: 1456: 1433: 1432: 1411: 1406: 1405: 1384: 1383: 1378: 1372: 1371: 1366: 1356: 1335: 1334: 1310: 1309: 1301: 1291: 1285: 1231: 1230: 1206: 1189: 1188: 1097: 1072: 1067: 1066: 1019: 1014: 1013: 1008:other than the 978: 973: 972: 935: 880: 869: 858: 857: 829: 812: 801: 800: 746: 726: 725: 705:is the ring of 676: 671: 670: 645: 640: 639: 615: 600: 595: 573: 558: 553: 537: 522: 517: 512: 511: 439:over some ring 347:, a nontrivial 338: 336:Semisimple ring 328: 264:linear operator 256: 228: 196:is one that is 190:complex numbers 131: 130: 128:linear operator 119:is semisimple. 105:. For example, 41:category theory 25:semi-simplicity 21: 12: 11: 5: 2088: 2086: 2078: 2077: 2072: 2067: 2062: 2060:Linear algebra 2052: 2051: 2048: 2047: 2035: 2024: 2023:External links 2021: 2020: 2019: 2007: 2006: 1994: 1982: 1970: 1958: 1938:(1): 239–261, 1930:-structures", 1918: 1903: 1882: 1867:pseudo-abelian 1858: 1850: 1830: 1815: 1805:Linear algebra 1789: 1773: 1772: 1770: 1767: 1766: 1765: 1760: 1755: 1748: 1739: 1736: 1714: 1690: 1668: 1648: 1628: 1602: 1574: 1550: 1528: 1508: 1484: 1464: 1440: 1418: 1414: 1402: 1401: 1388: 1382: 1379: 1377: 1374: 1373: 1370: 1367: 1365: 1362: 1361: 1359: 1354: 1351: 1348: 1345: 1342: 1318: 1287:Main article: 1284: 1281: 1238: 1213: 1209: 1205: 1202: 1199: 1196: 1136: 1135: 1124: 1121: 1118: 1115: 1112: 1109: 1104: 1100: 1096: 1093: 1090: 1087: 1084: 1079: 1075: 1026: 1022: 993: 990: 985: 981: 934: 931: 886: 883: 879: 875: 872: 868: 865: 854: 853: 842: 839: 835: 832: 828: 825: 822: 818: 815: 811: 808: 767: 764: 761: 758: 753: 749: 745: 742: 739: 736: 733: 694: 691: 688: 683: 679: 652: 648: 627: 622: 618: 614: 607: 603: 598: 594: 591: 588: 585: 580: 576: 572: 565: 561: 556: 552: 549: 544: 540: 536: 529: 525: 520: 485:characteristic 375:-submodule of 327: 324: 255: 252: 238:, such as the 227: 224: 206:diagonalizable 150: 147: 144: 141: 138: 98:characteristic 80:is said to be 71:representation 29:linear algebra 13: 10: 9: 6: 4: 3: 2: 2087: 2076: 2073: 2071: 2068: 2066: 2063: 2061: 2058: 2057: 2055: 2046: 2044: 2039: 2036: 2034: 2030: 2027: 2026: 2022: 2016: 2011: 2010: 2003: 1998: 1995: 1991: 1986: 1983: 1979: 1974: 1971: 1967: 1962: 1959: 1955: 1951: 1946: 1941: 1937: 1933: 1929: 1922: 1919: 1915: 1914: 1910:Uwe Jannsen: 1907: 1904: 1900: 1896: 1892: 1886: 1883: 1879: 1875: 1871: 1868: 1862: 1859: 1853: 1851:0-387-95183-0 1847: 1843: 1842: 1834: 1831: 1826: 1822: 1818: 1816:9780135367971 1812: 1807: 1806: 1800: 1793: 1790: 1787: 1781: 1779: 1775: 1768: 1764: 1761: 1759: 1756: 1753: 1749: 1746: 1742: 1741: 1737: 1735: 1733: 1728: 1666: 1646: 1626: 1618: 1591:: Every such 1590: 1498: 1497:inner product 1482: 1454: 1438: 1416: 1412: 1386: 1380: 1375: 1368: 1363: 1357: 1352: 1346: 1333: 1332: 1331: 1306: 1300: 1296: 1290: 1282: 1280: 1278: 1274: 1270: 1268: 1262: 1260: 1256: 1253:and shown by 1252: 1236: 1229: 1211: 1203: 1197: 1194: 1187: 1184:over a field 1183: 1180: 1176: 1175: 1169: 1168:bilinear form 1166: 1162: 1161: 1155: 1150: 1148: 1144: 1139: 1119: 1116: 1113: 1107: 1102: 1098: 1094: 1088: 1082: 1077: 1073: 1065: 1064: 1063: 1062: 1058: 1057:Schur's lemma 1054: 1050: 1046: 1042: 1024: 1020: 1011: 1007: 991: 988: 983: 979: 970: 967: 962: 960: 956: 953:-modules and 952: 948: 945:. Briefly, a 944: 940: 932: 930: 928: 924: 920: 917: 913: 909: 905: 901: 884: 881: 877: 873: 870: 866: 863: 840: 833: 830: 823: 816: 813: 806: 799: 798: 797: 796: 791: 789: 785: 784:endomorphisms 781: 762: 756: 751: 747: 743: 737: 731: 723: 718: 716: 712: 708: 689: 681: 677: 668: 667:division ring 650: 646: 638:, where each 620: 616: 605: 601: 596: 592: 589: 586: 578: 574: 563: 559: 554: 550: 542: 538: 527: 523: 518: 509: 506: 505:Artinian ring 502: 498: 494: 490: 486: 482: 478: 474: 470: 466: 462: 458: 454: 450: 446: 442: 438: 435: 431: 428: 423: 421: 417: 414: 410: 406: 402: 398: 394: 390: 386: 382: 378: 374: 370: 366: 362: 358: 354: 350: 346: 343: 337: 333: 325: 323: 321: 317: 313: 309: 304: 302: 298: 294: 291: 290:complementary 287: 283: 279: 275: 272: 268: 265: 261: 260:square matrix 253: 251: 249: 245: 241: 237: 233: 232:vector spaces 225: 223: 221: 217: 214: 209: 207: 203: 199: 195: 191: 188:(such as the 187: 183: 179: 175: 172: 168: 164: 148: 142: 139: 136: 129: 125: 124:square matrix 120: 118: 115: 112: 108: 104: 99: 95: 91: 87: 83: 79: 75: 72: 68: 65: 61: 56: 54: 50: 46: 42: 38: 34: 30: 26: 19: 2042: 2029:MathOverflow 2014: 1997: 1992:Theorem 10.9 1985: 1980:Theorem 4.28 1973: 1968:Example 4.25 1961: 1935: 1931: 1927: 1921: 1911: 1906: 1890: 1885: 1873: 1861: 1840: 1833: 1804: 1792: 1784:Lam (2001), 1729: 1403: 1302: 1266: 1263: 1251:Grothendieck 1185: 1171: 1157: 1154:Hodge theory 1151: 1146: 1142: 1140: 1137: 1044: 1040: 968: 963: 958: 954: 950: 942: 938: 936: 926: 922: 918: 915: 911: 907: 855: 792: 787: 779: 721: 720:An operator 719: 714: 710: 706: 507: 496: 492: 488: 480: 476: 468: 464: 456: 452: 448: 444: 440: 436: 426: 424: 419: 415: 408: 403:is called a 400: 396: 392: 388: 384: 380: 376: 372: 364: 360: 356: 352: 348: 344: 340:For a fixed 339: 311: 305: 300: 292: 281: 277: 273: 271:vector space 266: 257: 240:real numbers 229: 210: 193: 181: 180:are {0} and 177: 169:if its only 166: 162: 121: 102: 85: 81: 73: 59: 57: 52: 48: 24: 22: 2070:Ring theory 2004:Theorem 5.6 1010:zero object 939:semi-simple 906:. The ring 503:, a unital 483:divide the 369:semi-simple 278:semi-simple 244:dimensional 213:semi-simple 2054:Categories 1954:1251.18006 1799:Kunze, Ray 1769:References 1730:See also: 1495:admits an 1293:See also: 1269:-structure 1226:modulo an 1049:direct sum 904:extensions 434:group ring 320:hyperplane 276:is called 248:direct sum 220:categories 111:semisimple 2002:Hall 2015 1990:Hall 2015 1978:Hall 2015 1966:Hall 2015 1527:Π 1507:Π 1463:Π 1341:Π 1330:given by 1237:∼ 1212:∼ 1198:⁡ 1108:⁡ 1083:⁡ 1059:that the 1053:coproduct 1025:α 1006:subobject 989:∈ 984:α 941:category 878:⊕ 867:≅ 838:→ 827:→ 821:→ 810:→ 757:⁡ 744:⊆ 593:× 590:⋯ 587:× 551:× 371:if every 280:if every 171:invariant 146:→ 117:Lie group 1738:See also 1639:. Since 947:category 885:″ 874:′ 834:″ 817:′ 418:-module 391:-module 363:-module 351:-module 234:(over a 2040:at the 1825:0276251 1679:and of 1453:compact 1255:Jannsen 1174:motives 1051:(i.e., 1047:is the 1043:object 216:modules 198:similar 114:compact 92:). Now 76:over a 1952:  1897:  1848:  1823:  1813:  1179:smooth 1012:0 and 379:is an 310:field 288:has a 176:under 167:simple 82:simple 64:finite 53:simple 43:, and 1786:p. 39 1275:on a 1172:pure 665:is a 359:. An 236:field 200:to a 161:with 78:field 67:group 62:is a 1895:ISBN 1846:ISBN 1811:ISBN 1297:and 921:and 709:-by- 669:and 481:does 342:ring 334:and 47:. A 2045:Lab 1950:Zbl 1940:doi 1475:of 1451:is 1195:Mot 1177:of 1099:Hom 1074:End 1041:any 964:An 786:of 748:End 487:of 467:on 463:of 367:is 299:of 2056:: 1948:, 1936:14 1934:, 1821:MR 1819:. 1777:^ 1750:A 1743:A 1279:. 961:. 929:. 717:. 479:| 395:, 258:A 222:. 208:. 122:A 39:, 35:, 31:, 2043:n 2031:: 1942:: 1928:t 1880:. 1854:. 1827:. 1713:g 1689:g 1667:K 1647:K 1627:K 1601:g 1573:g 1549:g 1483:G 1439:G 1417:1 1413:e 1387:) 1381:1 1376:0 1369:x 1364:1 1358:( 1353:= 1350:) 1347:x 1344:( 1317:R 1267:t 1208:) 1204:k 1201:( 1186:k 1147:R 1143:R 1123:) 1120:X 1117:, 1114:X 1111:( 1103:C 1095:= 1092:) 1089:X 1086:( 1078:C 1045:X 1021:X 992:C 980:X 969:C 959:R 955:R 951:R 943:C 927:n 925:/ 923:Z 919:Z 916:n 912:Z 908:Z 882:M 871:M 864:M 841:0 831:M 824:M 814:M 807:0 788:V 780:T 766:) 763:V 760:( 752:F 741:] 738:T 735:[ 732:F 722:T 715:D 711:n 707:n 693:) 690:D 687:( 682:n 678:M 651:i 647:D 626:) 621:r 617:D 613:( 606:r 602:n 597:M 584:) 579:2 575:D 571:( 564:2 560:n 555:M 548:) 543:1 539:D 535:( 528:1 524:n 519:M 508:R 497:R 493:G 489:R 477:G 469:R 465:G 457:R 453:R 449:G 445:R 441:R 437:R 427:G 420:M 416:R 409:R 401:R 397:M 393:M 389:R 385:M 381:R 377:M 373:R 365:M 361:R 357:M 353:M 349:R 345:R 312:F 301:T 293:T 284:- 282:T 274:V 267:T 182:V 178:T 163:V 149:V 143:V 140:: 137:T 86:V 74:V 60:G 20:.

Index

Reduction (philosophy)
linear algebra
abstract algebra
representation theory
category theory
algebraic geometry
finite
group
representation
field
irreducible representations
Maschke's theorem
characteristic
Weyl's theorem on complete reducibility
semisimple
compact
Lie group
square matrix
linear operator
invariant
linear subspaces
algebraically closed
complex numbers
similar
direct sum of simple matrices
diagonalizable
semi-simple
modules
categories
vector spaces

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