Knowledge

Group representation

Source 📝

1555: 1311: 1788: 228:— Many important Lie groups are compact, so the results of compact representation theory apply to them. Other techniques specific to Lie groups are used as well. Most of the groups important in physics and chemistry are Lie groups, and their representation theory is crucial to the application of group theory in those fields. See 200:— Many of the results of finite group representation theory are proved by averaging over the group. These proofs can be carried over to infinite groups by replacement of the average with an integral, provided that an acceptable notion of integral can be defined. This can be done for locally compact groups, using the 1365: 259:. Although linear algebraic groups have a classification that is very similar to that of Lie groups, and give rise to the same families of Lie algebras, their representations are rather different (and much less well understood). The analytic techniques used for studying Lie groups must be replaced by techniques from 1121: 1602: 38: 149:
The representation theory of groups divides into subtheories depending on the kind of group being represented. The various theories are quite different in detail, though some basic definitions and concepts are similar. The most important divisions are:
1550:{\displaystyle \sigma \left(1\right)={\begin{bmatrix}1&0\\0&1\\\end{bmatrix}}\qquad \sigma \left(u\right)={\begin{bmatrix}u&0\\0&1\\\end{bmatrix}}\qquad \sigma \left(u^{2}\right)={\begin{bmatrix}u^{2}&0\\0&1\\\end{bmatrix}}.} 1306:{\displaystyle \rho \left(1\right)={\begin{bmatrix}1&0\\0&1\\\end{bmatrix}}\qquad \rho \left(u\right)={\begin{bmatrix}1&0\\0&u\\\end{bmatrix}}\qquad \rho \left(u^{2}\right)={\begin{bmatrix}1&0\\0&u^{2}\\\end{bmatrix}}.} 583: 1893: 1783:{\displaystyle \tau \left(1\right)={\begin{bmatrix}1&0\\0&1\\\end{bmatrix}}\qquad \tau \left(u\right)={\begin{bmatrix}a&-b\\b&a\\\end{bmatrix}}\qquad \tau \left(u^{2}\right)={\begin{bmatrix}a&b\\-b&a\\\end{bmatrix}}} 2779: 2205:
In the example above, the first two representations given (ρ and σ) are both decomposable into two 1-dimensional subrepresentations (given by span{(1,0)} and span{(0,1)}), while the third representation (τ) is irreducible.
303:
on which the group acts. One distinguishes between finite-dimensional representations and infinite-dimensional ones. In the infinite-dimensional case, additional structures are important (e.g. whether or not the space is a
863: 1047: 449: 2447: 273:— The class of non-compact groups is too broad to construct any general representation theory, but specific special cases have been studied, sometimes using ad hoc techniques. The 1975: 1594: 1357: 1113: 121:
is also used in a more general sense to mean any "description" of a group as a group of transformations of some mathematical object. More formally, a "representation" means a
460: 2332: 2117: 2085: 1799: 671: 2004: 2053: 2470: 2024: 1919: 2868: 141:
for the special case of linear representations. The bulk of this article describes linear representation theory; see the last section for generalizations.
159:— Group representations are a very important tool in the study of finite groups. They also arise in the applications of finite group theory to 791: 2167:. The representation of dimension zero is considered to be neither reducible nor irreducible, just as the number 1 is considered to be neither 983: 2895: 406: 393: 2621:, this definition is equivalent to a linear representation. Likewise, a set-theoretic representation is just a representation of 95:
In chemistry, a group representation can relate mathematical group elements to symmetric rotations and reflections of molecules.
2754: 185: 2836: 343:
of the field is also significant; many theorems for finite groups depend on the characteristic of the field not dividing the
17: 2749: 2338: 2744: 233: 2890: 2808: 2655: 756: 2820: 229: 180: 2724: 1924: 2812: 2641: 2518: 2142: 2128: 292: 1570: 1333: 1089: 2759: 2685: 2614: 2202:, since the characteristic of the complex numbers is zero, which never divides the size of a group. 578:{\displaystyle \rho (g_{1}g_{2})=\rho (g_{1})\rho (g_{2}),\qquad {\text{for all }}g_{1},g_{2}\in G.} 2179: 697: 340: 168: 1888:{\displaystyle a={\text{Re}}(u)=-{\tfrac {1}{2}},\qquad b={\text{Im}}(u)={\tfrac {\sqrt {3}}{2}}.} 872: 31: 2872:. Translated from the 1985 Russian-language edition (Kharkov, Ukraine). Birkhäuser Verlag. 1988. 2293: 2534: 2242: 2090: 2058: 650: 624: 240: 217: 2163:; if it has a proper subrepresentation of nonzero dimension, the representation is said to be 281:
Lie groups cannot be classified in the same way. The general theory for Lie groups deals with
2885: 2699: 196: 89: 73: 58: 2846: 2195: 2191: 1982: 344: 336: 2032: 8: 2228: 374: 360: 316: 164: 66: 42: 251:) — These are the analogues of Lie groups, but over more general fields than just 2739: 2590: 2497: 2455: 2009: 1921:
be the space of homogeneous degree-3 polynomials over the complex numbers in variables
1904: 381: 282: 260: 209: 126: 2850: 2832: 2235: 2147: 689: 673: 213: 205: 85: 2824: 2734: 2689: 2626: 2168: 264: 2842: 2729: 2711: 2707: 2501: 2199: 160: 319:
over which the vector space is defined. The most important case is the field of
114:
of a physical system affects the solutions of equations describing that system.
320: 111: 103: 46: 2828: 2198:). This holds in particular for any representation of a finite group over the 612:
itself as the representation when the homomorphism is clear from the context.
2879: 2854: 2671: 2155:
has exactly two subrepresentations, namely the zero-dimensional subspace and
332: 305: 287: 192: 2681:
Two types of representations closely related to linear representations are:
858:{\displaystyle \ker \rho =\left\{g\in G\mid \rho (g)=\mathrm {id} \right\}.} 2703: 2187: 2172: 1083: 367: 328: 324: 309: 300: 247: 201: 155: 122: 99: 81: 77: 2485: 950: 54: 2860: 2496:. Thus we may equivalently define a permutation representation to be a 224: 37: 2823:, Readings in Mathematics. Vol. 129. New York: Springer-Verlag. 2481: 1317: 887: 70: 339:
fields are easier to handle than non-algebraically closed ones. The
277:
have a deep theory, building on the compact case. The complementary
27:
Group homomorphism into the general linear group over a vector space
2645: 2538: 84:); in particular, they can be used to represent group elements as 2562: 107: 49:, consisting of reflections and rotations, transform the polygon. 1042:{\displaystyle \alpha \circ \rho (g)\circ \alpha ^{-1}=\pi (g).} 2869:
Introduction to the Theory of Banach Representations of Groups
212:
describes the theory for commutative groups, as a generalised
2693: 890:; in other words, one whose kernel is the trivial subgroup { 444:{\displaystyle \rho \colon G\to \mathrm {GL} \left(V\right)} 1086:
under multiplication. This group has a representation ρ on
2186:
does not divide the size of the group, representations of
299:
Representation theory also depends heavily on the type of
144: 2859:. Introduction to representation theory with emphasis on 2476:. This condition and the axioms for a group imply that ρ( 608:
of the representation. It is common practice to refer to
129:
of an object. If the object is a vector space we have a
184:; this special case has very different properties. See 2524: 2517:
For more information on this topic see the article on
1869: 1830: 1746: 1682: 1628: 1506: 1445: 1391: 1262: 1201: 1147: 2458: 2341: 2296: 2093: 2061: 2035: 2012: 1985: 1927: 1907: 1802: 1605: 1573: 1368: 1336: 1124: 1092: 986: 794: 653: 463: 409: 285:
of the two types, by means of general results called
2692:. These can be described as "linear representations 178:
divides the order of the group, then this is called
2464: 2441: 2326: 2214: 2111: 2079: 2047: 2018: 1998: 1969: 1913: 1887: 1782: 1588: 1549: 1351: 1305: 1107: 1041: 894:} consisting only of the group's identity element. 857: 665: 577: 443: 88:so that the group operation can be represented by 1359:, isomorphic to the previous one, is σ given by: 45:"acts" on an object. A simple example is how the 2877: 2442:{\displaystyle \rho (g_{1}g_{2})=\rho (g_{1})],} 1316:This representation is faithful because ρ is a 2159:itself, then the representation is said to be 323:. The other important cases are the field of 2807: 204:. The resulting theory is a central part of 137:for the general notion and reserve the term 2541:in this category are just the elements of 1576: 1339: 1095: 36: 2194:of irreducible subrepresentations (see 2026:by permutation of the three variables. 400:. That is, a representation is a map 145:Branches of group representation theory 14: 2878: 2755:Representation theory of finite groups 1567:may also be faithfully represented on 186:Representation theory of finite groups 102:problems to be reduced to problems in 2817:Representation theory. A first course 774:is defined as the normal subgroup of 98:Representations of groups allow many 2750:List of representation theory topics 267:causes many technical complications. 2573:. Such a functor selects an object 2525:Representations in other categories 315:One must also consider the type of 167:of scalars of the vector space has 24: 2644:, the objects obtained are called 2209: 1970:{\displaystyle x_{1},x_{2},x_{3}.} 843: 840: 426: 423: 25: 2907: 2654:For another example consider the 2223:(also known as a group action or 875:is one in which the homomorphism 2745:List of harmonic analysis topics 1589:{\displaystyle \mathbb {R} ^{2}} 1352:{\displaystyle \mathbb {C} ^{2}} 1108:{\displaystyle \mathbb {C} ^{2}} 2896:Representation theory of groups 2215:Set-theoretical representations 2122: 1844: 1716: 1659: 1476: 1422: 1232: 1178: 949:if there exists a vector space 782:is the identity transformation: 537: 291:, which is a generalization of 234:Representations of Lie algebras 47:symmetries of a regular polygon 2772: 2656:category of topological spaces 2581:and a group homomorphism from 2545:. Given an arbitrary category 2433: 2430: 2424: 2421: 2408: 2402: 2399: 2386: 2377: 2371: 2368: 2345: 2315: 2309: 2306: 2300: 2178:Under the assumption that the 2042: 2036: 1862: 1856: 1820: 1814: 1033: 1027: 1002: 996: 833: 827: 531: 518: 512: 499: 490: 467: 419: 350: 271:Non-compact topological groups 13: 1: 2821:Graduate Texts in Mathematics 2801: 2674:group of a topological space 230:Representations of Lie groups 181:modular representation theory 80:to itself (i.e. vector space 2253:, the set of functions from 2221:set-theoretic representation 2141:that is invariant under the 1059:Consider the complex number 263:, where the relatively weak 7: 2725:Irreducible representations 2718: 2472:is the identity element of 1323:Another representation for 1063:= e which has the property 1054: 10: 2912: 2686:projective representations 2642:category of abelian groups 2327:{\displaystyle \rho (1)=x} 2225:permutation representation 2129:Irreducible representation 2126: 716:such that the application 29: 2829:10.1007/978-1-4612-0979-9 2760:Semisimple representation 2615:category of vector spaces 2190:can be decomposed into a 2112:{\displaystyle x_{2}^{3}} 2080:{\displaystyle x_{1}^{3}} 702:continuous representation 666:{\displaystyle n\times n} 623:it is common to choose a 119:representation of a group 2765: 2696:scalar transformations". 698:topological vector space 163:and to geometry. If the 110:, they describe how the 30:Not to be confused with 2666:are homomorphisms from 873:faithful representation 619:is of finite dimension 293:Wigner's classification 241:Linear algebraic groups 32:Presentation of a group 2780:"1.4: Representations" 2700:affine representations 2537:with a single object; 2466: 2443: 2328: 2113: 2081: 2049: 2020: 2000: 1971: 1915: 1889: 1784: 1590: 1551: 1353: 1307: 1109: 1043: 911:, two representations 859: 667: 579: 445: 197:locally compact groups 125:from the group to the 74:linear transformations 50: 41:A representation of a 2891:Representation theory 2702:: in the category of 2688:: in the category of 2662:. Representations in 2467: 2444: 2329: 2114: 2082: 2050: 2021: 2001: 1999:{\displaystyle S_{3}} 1972: 1916: 1890: 1785: 1591: 1552: 1354: 1308: 1110: 1044: 860: 668: 596:and the dimension of 580: 446: 275:semisimple Lie groups 131:linear representation 90:matrix multiplication 63:group representations 59:representation theory 40: 18:Group representations 2784:Chemistry LibreTexts 2456: 2339: 2294: 2261:, such that for all 2091: 2059: 2048:{\displaystyle (12)} 2033: 2010: 1983: 1925: 1905: 1800: 1603: 1571: 1366: 1334: 1122: 1090: 984: 792: 766:of a representation 712:is a representation 651: 594:representation space 461: 407: 394:general linear group 337:algebraically closed 244:(or more generally 2710:acts affinely upon 2706:. For example, the 2533:can be viewed as a 2108: 2076: 674:invertible matrices 283:semidirect products 86:invertible matrices 2866:Yurii I. Lyubich. 2740:Molecular symmetry 2600:In the case where 2591:automorphism group 2498:group homomorphism 2462: 2439: 2324: 2109: 2094: 2077: 2062: 2045: 2016: 1996: 1967: 1911: 1885: 1880: 1839: 1780: 1774: 1710: 1653: 1586: 1547: 1538: 1470: 1416: 1349: 1303: 1294: 1226: 1172: 1105: 1039: 855: 778:whose image under 663: 615:In the case where 575: 441: 382:group homomorphism 345:order of the group 261:algebraic geometry 218:Peter–Weyl theorem 210:Pontryagin duality 133:. Some people use 127:automorphism group 65:describe abstract 51: 2838:978-0-387-97495-8 2690:projective spaces 2465:{\displaystyle 1} 2196:Maschke's theorem 2148:subrepresentation 2019:{\displaystyle V} 1914:{\displaystyle V} 1898:Another example: 1879: 1875: 1854: 1838: 1812: 690:topological group 541: 214:Fourier transform 206:harmonic analysis 16:(Redirected from 2903: 2858: 2795: 2794: 2792: 2791: 2776: 2735:Character theory 2627:category of sets 2471: 2469: 2468: 2463: 2448: 2446: 2445: 2440: 2420: 2419: 2398: 2397: 2367: 2366: 2357: 2356: 2333: 2331: 2330: 2325: 2118: 2116: 2115: 2110: 2107: 2102: 2086: 2084: 2083: 2078: 2075: 2070: 2054: 2052: 2051: 2046: 2025: 2023: 2022: 2017: 2005: 2003: 2002: 1997: 1995: 1994: 1976: 1974: 1973: 1968: 1963: 1962: 1950: 1949: 1937: 1936: 1920: 1918: 1917: 1912: 1894: 1892: 1891: 1886: 1881: 1871: 1870: 1855: 1852: 1840: 1831: 1813: 1810: 1789: 1787: 1786: 1781: 1779: 1778: 1737: 1733: 1732: 1715: 1714: 1673: 1658: 1657: 1619: 1595: 1593: 1592: 1587: 1585: 1584: 1579: 1556: 1554: 1553: 1548: 1543: 1542: 1518: 1517: 1497: 1493: 1492: 1475: 1474: 1436: 1421: 1420: 1382: 1358: 1356: 1355: 1350: 1348: 1347: 1342: 1312: 1310: 1309: 1304: 1299: 1298: 1291: 1290: 1253: 1249: 1248: 1231: 1230: 1192: 1177: 1176: 1138: 1114: 1112: 1111: 1106: 1104: 1103: 1098: 1048: 1046: 1045: 1040: 1020: 1019: 966:so that for all 965: 940: 925: 885: 864: 862: 861: 856: 851: 847: 846: 754: 730: 672: 670: 669: 664: 646: 631:and identify GL( 584: 582: 581: 576: 565: 564: 552: 551: 542: 539: 530: 529: 511: 510: 489: 488: 479: 478: 450: 448: 447: 442: 440: 429: 331:, and fields of 265:Zariski topology 21: 2911: 2910: 2906: 2905: 2904: 2902: 2901: 2900: 2876: 2875: 2839: 2809:Fulton, William 2804: 2799: 2798: 2789: 2787: 2778: 2777: 2773: 2768: 2730:Character table 2721: 2712:Euclidean space 2708:Euclidean group 2612: 2527: 2509: 2502:symmetric group 2457: 2454: 2453: 2415: 2411: 2393: 2389: 2362: 2358: 2352: 2348: 2340: 2337: 2336: 2295: 2292: 2291: 2274: 2267: 2217: 2212: 2210:Generalizations 2200:complex numbers 2131: 2125: 2103: 2098: 2092: 2089: 2088: 2071: 2066: 2060: 2057: 2056: 2034: 2031: 2030: 2011: 2008: 2007: 1990: 1986: 1984: 1981: 1980: 1958: 1954: 1945: 1941: 1932: 1928: 1926: 1923: 1922: 1906: 1903: 1902: 1868: 1851: 1829: 1809: 1801: 1798: 1797: 1773: 1772: 1767: 1758: 1757: 1752: 1742: 1741: 1728: 1724: 1720: 1709: 1708: 1703: 1697: 1696: 1688: 1678: 1677: 1663: 1652: 1651: 1646: 1640: 1639: 1634: 1624: 1623: 1609: 1604: 1601: 1600: 1596:by τ given by: 1580: 1575: 1574: 1572: 1569: 1568: 1566: 1537: 1536: 1531: 1525: 1524: 1519: 1513: 1509: 1502: 1501: 1488: 1484: 1480: 1469: 1468: 1463: 1457: 1456: 1451: 1441: 1440: 1426: 1415: 1414: 1409: 1403: 1402: 1397: 1387: 1386: 1372: 1367: 1364: 1363: 1343: 1338: 1337: 1335: 1332: 1331: 1329: 1293: 1292: 1286: 1282: 1280: 1274: 1273: 1268: 1258: 1257: 1244: 1240: 1236: 1225: 1224: 1219: 1213: 1212: 1207: 1197: 1196: 1182: 1171: 1170: 1165: 1159: 1158: 1153: 1143: 1142: 1128: 1123: 1120: 1119: 1099: 1094: 1093: 1091: 1088: 1087: 1073: 1057: 1012: 1008: 985: 982: 981: 953: 941:are said to be 927: 912: 876: 839: 811: 807: 793: 790: 789: 732: 717: 652: 649: 648: 647:, the group of 636: 560: 556: 547: 543: 538: 525: 521: 506: 502: 484: 480: 474: 470: 462: 459: 458: 430: 422: 408: 405: 404: 353: 321:complex numbers 161:crystallography 147: 100:group-theoretic 35: 28: 23: 22: 15: 12: 11: 5: 2909: 2899: 2898: 2893: 2888: 2874: 2873: 2864: 2837: 2803: 2800: 2797: 2796: 2770: 2769: 2767: 2764: 2763: 2762: 2757: 2752: 2747: 2742: 2737: 2732: 2727: 2720: 2717: 2716: 2715: 2697: 2608: 2551:representation 2526: 2523: 2505: 2500:from G to the 2461: 2450: 2449: 2438: 2435: 2432: 2429: 2426: 2423: 2418: 2414: 2410: 2407: 2404: 2401: 2396: 2392: 2388: 2385: 2382: 2379: 2376: 2373: 2370: 2365: 2361: 2355: 2351: 2347: 2344: 2334: 2323: 2320: 2317: 2314: 2311: 2308: 2305: 2302: 2299: 2272: 2265: 2241:is given by a 2216: 2213: 2211: 2208: 2180:characteristic 2127:Main article: 2124: 2121: 2106: 2101: 2097: 2074: 2069: 2065: 2044: 2041: 2038: 2029:For instance, 2015: 1993: 1989: 1966: 1961: 1957: 1953: 1948: 1944: 1940: 1935: 1931: 1910: 1896: 1895: 1884: 1878: 1874: 1867: 1864: 1861: 1858: 1850: 1847: 1843: 1837: 1834: 1828: 1825: 1822: 1819: 1816: 1808: 1805: 1791: 1790: 1777: 1771: 1768: 1766: 1763: 1760: 1759: 1756: 1753: 1751: 1748: 1747: 1745: 1740: 1736: 1731: 1727: 1723: 1719: 1713: 1707: 1704: 1702: 1699: 1698: 1695: 1692: 1689: 1687: 1684: 1683: 1681: 1676: 1672: 1669: 1666: 1662: 1656: 1650: 1647: 1645: 1642: 1641: 1638: 1635: 1633: 1630: 1629: 1627: 1622: 1618: 1615: 1612: 1608: 1583: 1578: 1564: 1558: 1557: 1546: 1541: 1535: 1532: 1530: 1527: 1526: 1523: 1520: 1516: 1512: 1508: 1507: 1505: 1500: 1496: 1491: 1487: 1483: 1479: 1473: 1467: 1464: 1462: 1459: 1458: 1455: 1452: 1450: 1447: 1446: 1444: 1439: 1435: 1432: 1429: 1425: 1419: 1413: 1410: 1408: 1405: 1404: 1401: 1398: 1396: 1393: 1392: 1390: 1385: 1381: 1378: 1375: 1371: 1346: 1341: 1327: 1318:one-to-one map 1314: 1313: 1302: 1297: 1289: 1285: 1281: 1279: 1276: 1275: 1272: 1269: 1267: 1264: 1263: 1261: 1256: 1252: 1247: 1243: 1239: 1235: 1229: 1223: 1220: 1218: 1215: 1214: 1211: 1208: 1206: 1203: 1202: 1200: 1195: 1191: 1188: 1185: 1181: 1175: 1169: 1166: 1164: 1161: 1160: 1157: 1154: 1152: 1149: 1148: 1146: 1141: 1137: 1134: 1131: 1127: 1102: 1097: 1071: 1056: 1053: 1052: 1051: 1050: 1049: 1038: 1035: 1032: 1029: 1026: 1023: 1018: 1015: 1011: 1007: 1004: 1001: 998: 995: 992: 989: 976: 975: 903:vector spaces 896: 895: 868: 867: 866: 865: 854: 850: 845: 842: 838: 835: 832: 829: 826: 823: 820: 817: 814: 810: 806: 803: 800: 797: 784: 783: 760: 662: 659: 656: 600:is called the 592:is called the 586: 585: 574: 571: 568: 563: 559: 555: 550: 546: 536: 533: 528: 524: 520: 517: 514: 509: 505: 501: 498: 495: 492: 487: 483: 477: 473: 469: 466: 452: 451: 439: 436: 433: 428: 425: 421: 418: 415: 412: 357:representation 352: 349: 341:characteristic 335:. In general, 333:p-adic numbers 297: 296: 268: 237: 221: 193:Compact groups 189: 169:characteristic 146: 143: 139:representation 112:symmetry group 104:linear algebra 26: 9: 6: 4: 3: 2: 2908: 2897: 2894: 2892: 2889: 2887: 2884: 2883: 2881: 2871: 2870: 2865: 2862: 2856: 2852: 2848: 2844: 2840: 2834: 2830: 2826: 2822: 2818: 2814: 2810: 2806: 2805: 2785: 2781: 2775: 2771: 2761: 2758: 2756: 2753: 2751: 2748: 2746: 2743: 2741: 2738: 2736: 2733: 2731: 2728: 2726: 2723: 2722: 2713: 2709: 2705: 2704:affine spaces 2701: 2698: 2695: 2691: 2687: 2684: 2683: 2682: 2679: 2677: 2673: 2672:homeomorphism 2669: 2665: 2661: 2657: 2652: 2650: 2648: 2643: 2639: 2635: 2630: 2628: 2624: 2620: 2617:over a field 2616: 2611: 2607: 2603: 2598: 2596: 2592: 2588: 2584: 2580: 2576: 2572: 2568: 2564: 2560: 2556: 2552: 2548: 2544: 2540: 2536: 2532: 2522: 2520: 2515: 2513: 2508: 2503: 2499: 2495: 2491: 2487: 2483: 2479: 2475: 2459: 2436: 2427: 2416: 2412: 2405: 2394: 2390: 2383: 2380: 2374: 2363: 2359: 2353: 2349: 2342: 2335: 2321: 2318: 2312: 2303: 2297: 2290: 2289: 2288: 2286: 2282: 2278: 2271: 2264: 2260: 2256: 2252: 2248: 2244: 2240: 2237: 2233: 2230: 2226: 2222: 2207: 2203: 2201: 2197: 2193: 2189: 2188:finite groups 2185: 2182:of the field 2181: 2176: 2174: 2170: 2166: 2162: 2158: 2154: 2150: 2149: 2144: 2140: 2136: 2130: 2120: 2104: 2099: 2095: 2072: 2067: 2063: 2039: 2027: 2013: 1991: 1987: 1977: 1964: 1959: 1955: 1951: 1946: 1942: 1938: 1933: 1929: 1908: 1899: 1882: 1876: 1872: 1865: 1859: 1848: 1845: 1841: 1835: 1832: 1826: 1823: 1817: 1806: 1803: 1796: 1795: 1794: 1775: 1769: 1764: 1761: 1754: 1749: 1743: 1738: 1734: 1729: 1725: 1721: 1717: 1711: 1705: 1700: 1693: 1690: 1685: 1679: 1674: 1670: 1667: 1664: 1660: 1654: 1648: 1643: 1636: 1631: 1625: 1620: 1616: 1613: 1610: 1606: 1599: 1598: 1597: 1581: 1563: 1544: 1539: 1533: 1528: 1521: 1514: 1510: 1503: 1498: 1494: 1489: 1485: 1481: 1477: 1471: 1465: 1460: 1453: 1448: 1442: 1437: 1433: 1430: 1427: 1423: 1417: 1411: 1406: 1399: 1394: 1388: 1383: 1379: 1376: 1373: 1369: 1362: 1361: 1360: 1344: 1326: 1321: 1319: 1300: 1295: 1287: 1283: 1277: 1270: 1265: 1259: 1254: 1250: 1245: 1241: 1237: 1233: 1227: 1221: 1216: 1209: 1204: 1198: 1193: 1189: 1186: 1183: 1179: 1173: 1167: 1162: 1155: 1150: 1144: 1139: 1135: 1132: 1129: 1125: 1118: 1117: 1116: 1100: 1085: 1081: 1077: 1070: 1067:= 1. The set 1066: 1062: 1036: 1030: 1024: 1021: 1016: 1013: 1009: 1005: 999: 993: 990: 987: 980: 979: 978: 977: 973: 969: 964: 960: 956: 952: 948: 944: 938: 934: 930: 923: 919: 915: 910: 906: 902: 898: 897: 893: 889: 883: 879: 874: 870: 869: 852: 848: 836: 830: 824: 821: 818: 815: 812: 808: 804: 801: 798: 795: 788: 787: 786: 785: 781: 777: 773: 769: 765: 761: 758: 752: 748: 744: 740: 736: 729: 725: 721: 715: 711: 707: 703: 699: 695: 691: 687: 683: 682: 681: 679: 676:on the field 675: 660: 657: 654: 644: 640: 634: 630: 626: 622: 618: 613: 611: 607: 603: 599: 595: 591: 572: 569: 566: 561: 557: 553: 548: 544: 540:for all  534: 526: 522: 515: 507: 503: 496: 493: 485: 481: 475: 471: 464: 457: 456: 455: 437: 434: 431: 416: 413: 410: 403: 402: 401: 399: 395: 391: 387: 383: 379: 376: 372: 369: 365: 362: 358: 348: 346: 342: 338: 334: 330: 329:finite fields 326: 322: 318: 313: 311: 307: 306:Hilbert space 302: 294: 290: 289: 288:Mackey theory 284: 280: 276: 272: 269: 266: 262: 258: 254: 250: 249: 248:group schemes 243: 242: 238: 235: 231: 227: 226: 222: 219: 215: 211: 207: 203: 199: 198: 194: 190: 187: 183: 182: 177: 173: 170: 166: 162: 158: 157: 156:Finite groups 153: 152: 151: 142: 140: 136: 132: 128: 124: 120: 115: 113: 109: 105: 101: 96: 93: 91: 87: 83: 82:automorphisms 79: 75: 72: 68: 64: 60: 56: 48: 44: 39: 33: 19: 2886:Group theory 2867: 2816: 2788:. Retrieved 2786:. 2019-09-04 2783: 2774: 2680: 2675: 2667: 2663: 2659: 2653: 2646: 2637: 2633: 2631: 2622: 2618: 2609: 2605: 2601: 2599: 2594: 2586: 2582: 2578: 2574: 2570: 2566: 2558: 2554: 2550: 2546: 2542: 2530: 2529:Every group 2528: 2519:group action 2516: 2511: 2506: 2493: 2489: 2477: 2473: 2451: 2284: 2280: 2276: 2269: 2262: 2258: 2254: 2250: 2246: 2238: 2231: 2224: 2220: 2218: 2204: 2183: 2177: 2164: 2160: 2156: 2152: 2146: 2145:is called a 2143:group action 2138: 2134: 2132: 2123:Reducibility 2028: 1978: 1900: 1897: 1792: 1561: 1559: 1324: 1322: 1315: 1084:cyclic group 1079: 1075: 1068: 1064: 1060: 1058: 971: 967: 962: 958: 954: 946: 942: 936: 932: 928: 921: 917: 913: 908: 904: 900: 891: 881: 877: 779: 775: 771: 767: 763: 750: 746: 742: 738: 734: 727: 723: 719: 713: 709: 705: 701: 693: 685: 677: 642: 638: 632: 628: 620: 616: 614: 609: 605: 601: 597: 593: 589: 587: 453: 397: 389: 385: 377: 370: 368:vector space 363: 356: 354: 325:real numbers 314: 310:Banach space 301:vector space 298: 286: 278: 274: 270: 256: 252: 245: 239: 223: 216:. See also: 202:Haar measure 191: 179: 175: 171: 154: 148: 138: 134: 130: 123:homomorphism 118: 116: 97: 94: 78:vector space 69:in terms of 62: 55:mathematical 52: 2813:Harris, Joe 2486:permutation 2161:irreducible 2133:A subspace 951:isomorphism 770:of a group 731:defined by 351:Definitions 135:realization 2880:Categories 2861:Lie groups 2802:References 2790:2021-06-23 2488:) for all 2192:direct sum 1560:The group 1115:given by: 1082:} forms a 947:isomorphic 943:equivalent 899:Given two 757:continuous 454:such that 225:Lie groups 2855:246650103 2539:morphisms 2482:bijection 2406:ρ 2384:ρ 2343:ρ 2298:ρ 2245:ρ : 2169:composite 2165:reducible 1827:− 1762:− 1718:τ 1691:− 1661:τ 1607:τ 1478:σ 1424:σ 1370:σ 1234:ρ 1180:ρ 1126:ρ 1025:π 1014:− 1010:α 1006:∘ 994:ρ 991:∘ 988:α 888:injective 825:ρ 822:∣ 816:∈ 802:ρ 799:⁡ 718:Φ : 658:× 602:dimension 567:∈ 516:ρ 497:ρ 465:ρ 420:→ 414:: 411:ρ 312:, etc.). 174:, and if 117:The term 71:bijective 57:field of 2815:(1991). 2719:See also 2649:-modules 2535:category 2279:and all 2243:function 2006:acts on 1055:Examples 957: : 931: : 916: : 295:methods. 279:solvable 2847:1153249 2670:to the 2625:in the 2589:), the 2585:to Aut( 2563:functor 2480:) is a 2227:) of a 635:) with 392:), the 373:over a 246:affine 108:physics 53:In the 2853:  2845:  2835:  2640:, the 2613:, the 2452:where 2055:sends 1793:where 1074:= {1, 764:kernel 606:degree 388:to GL( 208:. The 67:groups 2766:Notes 2694:up to 2632:When 2565:from 2561:is a 2234:on a 2229:group 2173:prime 2151:. If 1979:Then 935:→ GL( 920:→ GL( 880:→ GL( 696:is a 688:is a 625:basis 588:Here 384:from 380:is a 375:field 366:on a 361:group 359:of a 317:field 165:field 106:. In 76:of a 43:group 2851:OCLC 2833:ISBN 2606:Vect 2549:, a 2484:(or 2171:nor 1901:Let 926:and 907:and 762:The 741:) = 700:, a 692:and 627:for 232:and 2825:doi 2664:Top 2660:Top 2636:is 2604:is 2593:of 2577:in 2569:to 2557:in 2553:of 2510:of 2492:in 2283:in 2275:in 2257:to 2236:set 2137:of 2087:to 1330:on 970:in 945:or 886:is 796:ker 755:is 708:on 704:of 684:If 637:GL( 604:or 396:on 255:or 195:or 2882:: 2849:. 2843:MR 2841:. 2831:. 2819:. 2811:; 2782:. 2678:. 2658:, 2651:. 2638:Ab 2629:. 2597:. 2521:. 2514:. 2287:: 2268:, 2249:→ 2219:A 2175:. 2119:. 2040:12 1853:Im 1811:Re 1320:. 1078:, 961:→ 871:A 749:)( 737:, 733:Φ( 726:→ 722:× 680:. 641:, 355:A 347:. 327:, 308:, 92:. 61:, 2863:. 2857:. 2827:: 2793:. 2714:. 2676:X 2668:G 2647:G 2634:C 2623:G 2619:K 2610:K 2602:C 2595:X 2587:X 2583:G 2579:C 2575:X 2571:C 2567:G 2559:C 2555:G 2547:C 2543:G 2531:G 2512:X 2507:X 2504:S 2494:G 2490:g 2478:g 2474:G 2460:1 2437:, 2434:] 2431:] 2428:x 2425:[ 2422:) 2417:2 2413:g 2409:( 2403:[ 2400:) 2395:1 2391:g 2387:( 2381:= 2378:] 2375:x 2372:[ 2369:) 2364:2 2360:g 2354:1 2350:g 2346:( 2322:x 2319:= 2316:] 2313:x 2310:[ 2307:) 2304:1 2301:( 2285:X 2281:x 2277:G 2273:2 2270:g 2266:1 2263:g 2259:X 2255:X 2251:X 2247:G 2239:X 2232:G 2184:K 2157:V 2153:V 2139:V 2135:W 2105:3 2100:2 2096:x 2073:3 2068:1 2064:x 2043:) 2037:( 2014:V 1992:3 1988:S 1965:. 1960:3 1956:x 1952:, 1947:2 1943:x 1939:, 1934:1 1930:x 1909:V 1883:. 1877:2 1873:3 1866:= 1863:) 1860:u 1857:( 1849:= 1846:b 1842:, 1836:2 1833:1 1824:= 1821:) 1818:u 1815:( 1807:= 1804:a 1776:] 1770:a 1765:b 1755:b 1750:a 1744:[ 1739:= 1735:) 1730:2 1726:u 1722:( 1712:] 1706:a 1701:b 1694:b 1686:a 1680:[ 1675:= 1671:) 1668:u 1665:( 1655:] 1649:1 1644:0 1637:0 1632:1 1626:[ 1621:= 1617:) 1614:1 1611:( 1582:2 1577:R 1565:3 1562:C 1545:. 1540:] 1534:1 1529:0 1522:0 1515:2 1511:u 1504:[ 1499:= 1495:) 1490:2 1486:u 1482:( 1472:] 1466:1 1461:0 1454:0 1449:u 1443:[ 1438:= 1434:) 1431:u 1428:( 1418:] 1412:1 1407:0 1400:0 1395:1 1389:[ 1384:= 1380:) 1377:1 1374:( 1345:2 1340:C 1328:3 1325:C 1301:. 1296:] 1288:2 1284:u 1278:0 1271:0 1266:1 1260:[ 1255:= 1251:) 1246:2 1242:u 1238:( 1228:] 1222:u 1217:0 1210:0 1205:1 1199:[ 1194:= 1190:) 1187:u 1184:( 1174:] 1168:1 1163:0 1156:0 1151:1 1145:[ 1140:= 1136:) 1133:1 1130:( 1101:2 1096:C 1080:u 1076:u 1072:3 1069:C 1065:u 1061:u 1037:. 1034:) 1031:g 1028:( 1022:= 1017:1 1003:) 1000:g 997:( 974:, 972:G 968:g 963:W 959:V 955:α 939:) 937:W 933:G 929:π 924:) 922:V 918:G 914:ρ 909:W 905:V 901:K 892:e 884:) 882:V 878:G 853:. 849:} 844:d 841:i 837:= 834:) 831:g 828:( 819:G 813:g 809:{ 805:= 780:ρ 776:G 772:G 768:ρ 759:. 753:) 751:v 747:g 745:( 743:ρ 739:v 735:g 728:V 724:V 720:G 714:ρ 710:V 706:G 694:V 686:G 678:K 661:n 655:n 645:) 643:K 639:n 633:V 629:V 621:n 617:V 610:V 598:V 590:V 573:. 570:G 562:2 558:g 554:, 549:1 545:g 535:, 532:) 527:2 523:g 519:( 513:) 508:1 504:g 500:( 494:= 491:) 486:2 482:g 476:1 472:g 468:( 438:) 435:V 432:( 427:L 424:G 417:G 398:V 390:V 386:G 378:K 371:V 364:G 257:C 253:R 236:. 220:. 188:. 176:p 172:p 34:. 20:)

Index

Group representations
Presentation of a group

group
symmetries of a regular polygon
mathematical
representation theory
groups
bijective
linear transformations
vector space
automorphisms
invertible matrices
matrix multiplication
group-theoretic
linear algebra
physics
symmetry group
homomorphism
automorphism group
Finite groups
crystallography
field
characteristic
modular representation theory
Representation theory of finite groups
Compact groups
locally compact groups
Haar measure
harmonic analysis

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