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Brauer's theorem on induced characters

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has an irreducible complex character of degree 2 which is not expressible as a non-negative integer combination of characters induced from linear characters of subgroups). An ingredient of the proof of Brauer's induction theorem is that when
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showed (in 1955) that no such induction theorem (with integer combinations of characters induced from linear characters) could be proved with a collection of subgroups smaller than the Brauer elementary subgroups.
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Brauer's induction theorem was proved in 1946, and there are now many alternative proofs. In 1986, Victor Snaith gave a proof by a radically different approach, topological in nature (an application of the
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integer combination of characters induced from linear characters of subgroups. In general, this is not the case. In fact, by a theorem of Taketa, if all characters of
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is a virtual character. This result, together with the fact that a virtual character θ is an irreducible character if and only if θ(1)
718: 130: 555:|-th root of unity). The set of integer combinations of characters induced from linear characters of Brauer elementary subgroups is an ideal 137: 994: 119: 215: 203: 234:|, but at the expense of expanding the collection of subgroups used. Some years after the proof of Brauer's theorem appeared, 717:). There has been related recent work on the question of finding natural and explicit forms of Brauer's theorem, notably by 817:) gives a means of constructing irreducible characters without explicitly constructing the associated representations. 752: 366:
functions it is important that the groups are cyclic and hence all characters are linear giving that the corresponding
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Another result between Artin's induction theorem and Brauer's induction theorem, also due to Brauer and also known as
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is an integer combination of characters which are each induced from trivial characters of cyclic subgroups of
714: 930: 790: 448: 576: 33: 677: 638: 523: 303: 852:(although solvability alone does not guarantee such expressions- for example, the solvable group 97: 334: 50: 814: 235: 741:
is a virtual character if and only if its restriction to each Brauer elementary subgroup of
825: 508:. These are direct products of cyclic groups and groups whose order is a power of a prime. 948: 908: 898: 8: 923: 934: 884: 612: 520:) (most proofs also make use of a slightly larger ring, Char*(G), which consists of 944: 904: 894: 821: 730: 505: 490: 442: 399: 199: 862: 829: 437:
Brauer's induction theorem shows that the character ring can be generated (as an
391: 191: 551:-combinations of irreducible characters, where ω is a primitive complex | 983: 438: 575:). Several proofs of the theorem, beginning with a proof due to Brauer and 516:
The proof of Brauer's induction theorem exploits the ring structure of Char(
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Its multiplication is given by the elementwise product of class functions.
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Explicit Brauer Induction: With Applications to Algebra and Number Theory
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Fundamental result in the branch of mathematics known as character theory
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An initial motivation for Brauer's induction theorem was application to
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Corrected reprint of the 1976 original, published by Academic Press.
567:), so the proof reduces to showing that the trivial character is in 86: 482: 504:
could be chosen from a very restricted collection, now called
733:, Brauer's induction theorem leads easily to his fundamental 929:. Cambridge Studies in Advanced Mathematics. Vol. 40. 815:
inner product on the ring of complex-valued class functions
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at a time, and constructing integer-valued elements of
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is induced from a linear character of some subgroup.
793: 755: 680: 641: 526: 451: 337: 306: 260: 390:) denote the subring of the ring of complex-valued 358:are induced from characters of cyclic subgroups of 111:. Unsourced material may be challenged and removed. 922: 805: 779: 697: 658: 607:Once this is achieved for every prime divisor of | 543: 469: 350: 319: 292: 780:{\displaystyle \langle \theta ,\theta \rangle =1} 981: 250:is the fact that the regular representation of 214:A precursor to Brauer's induction theorem was 878: 800: 794: 768: 756: 293:{\displaystyle 1+\sum \lambda _{i}\rho _{i}} 611:|, some manipulations with congruences and 591:) by concentrating attention on one prime 500:In fact, Brauer showed that the subgroups 865:, every complex irreducible character of 682: 666:-valued class function lies in the ideal 643: 528: 171:Learn how and when to remove this message 69:Learn how and when to remove this message 824:. It shows that those are built up from 120:"Brauer's theorem on induced characters" 32:This article includes a list of general 204:representation theory of a finite group 990:Representation theory of finite groups 982: 920: 674:) if its values are all divisible (in 635:). An auxiliary result here is that a 398:consisting of integer combinations of 184:Brauer's theorem on induced characters 230:Brauer's theorem removes the factor | 194:, is a basic result in the branch of 109:adding citations to reliable sources 80: 18: 13: 914: 627:), place the trivial character in 38:it lacks sufficient corresponding 14: 1006: 995:Theorems in representation theory 881:Character Theory of Finite Groups 806:{\displaystyle \langle ,\rangle } 615:, again exploiting the fact that 222:| times the trivial character of 470:{\displaystyle \lambda _{H}^{G}} 414:, and its elements are known as 85: 23: 724: 96:needs additional citations for 963: 735:characterization of characters 692: 686: 653: 647: 538: 532: 1: 872: 715:Lefschetz fixed-point theorem 209: 698:{\displaystyle \mathbb {Z} } 659:{\displaystyle \mathbb {Z} } 544:{\displaystyle \mathbb {Z} } 373: 320:{\displaystyle \lambda _{i}} 7: 506:Brauer elementary subgroups 10: 1011: 931:Cambridge University Press 188:Brauer's induction theorem 973:, appendix to chapter XVI 844:are so expressible, then 511: 370:functions are analytic). 351:{\displaystyle \rho _{i}} 216:Artin's induction theorem 956: 430:is again a character of 971:Algebraic Number Theory 489:and λ ranges over 53:more precise citations. 921:Snaith, V. P. (1994). 879:Isaacs, I.M. (1994) . 807: 781: 699: 660: 545: 471: 420:generalized characters 400:irreducible characters 352: 321: 294: 218:, which states that | 826:Dirichlet L-functions 808: 782: 731:Frobenius reciprocity 700: 661: 623:) is an ideal of Ch*( 546: 493:(having degree 1) of 472: 424:difference characters 353: 322: 295: 791: 753: 678: 639: 524: 449: 335: 304: 258: 105:improve this article 466: 418:(alternatively, as 828:, or more general 803: 777: 695: 656: 613:algebraic integers 541: 467: 452: 443:induced characters 416:virtual characters 406:) is known as the 348: 329:positive rationals 317: 290: 254:can be written as 190:, and named after 830:Hecke L-functions 822:Artin L-functions 491:linear characters 186:, often known as 181: 180: 173: 155: 79: 78: 71: 1002: 974: 967: 952: 928: 902: 812: 810: 809: 804: 786: 784: 783: 778: 704: 702: 701: 696: 685: 665: 663: 662: 657: 646: 550: 548: 547: 542: 531: 476: 474: 473: 468: 465: 460: 357: 355: 354: 349: 347: 346: 326: 324: 323: 318: 316: 315: 299: 297: 296: 291: 289: 288: 279: 278: 244:Brauer's theorem 200:character theory 176: 169: 165: 162: 156: 154: 113: 89: 81: 74: 67: 63: 60: 54: 49:this article by 40:inline citations 27: 26: 19: 1010: 1009: 1005: 1004: 1003: 1001: 1000: 999: 980: 979: 978: 977: 968: 964: 959: 941: 917: 915:Further reading 891: 875: 863:nilpotent group 792: 789: 788: 754: 751: 750: 727: 681: 679: 676: 675: 642: 640: 637: 636: 527: 525: 522: 521: 514: 461: 456: 450: 447: 446: 422:, or sometimes 392:class functions 376: 342: 338: 336: 333: 332: 311: 307: 305: 302: 301: 284: 280: 274: 270: 259: 256: 255: 212: 177: 166: 160: 157: 114: 112: 102: 90: 75: 64: 58: 55: 45:Please help to 44: 28: 24: 17: 12: 11: 5: 1008: 998: 997: 992: 976: 975: 961: 960: 958: 955: 954: 953: 939: 916: 913: 912: 911: 889: 874: 871: 850:solvable group 802: 799: 796: 776: 773: 770: 767: 764: 761: 758: 726: 723: 694: 691: 688: 684: 655: 652: 649: 645: 540: 537: 534: 530: 513: 510: 464: 459: 455: 408:character ring 375: 372: 345: 341: 314: 310: 287: 283: 277: 273: 269: 266: 263: 248:Brauer's lemma 211: 208: 192:Richard Brauer 179: 178: 93: 91: 84: 77: 76: 31: 29: 22: 15: 9: 6: 4: 3: 2: 1007: 996: 993: 991: 988: 987: 985: 972: 966: 962: 950: 946: 942: 940:0-521-46015-8 936: 932: 927: 926: 919: 918: 910: 906: 900: 896: 892: 890:0-486-68014-2 886: 882: 877: 876: 870: 868: 864: 860: 855: 851: 847: 843: 839: 835: 831: 827: 823: 818: 816: 813:is the usual 797: 774: 771: 765: 762: 759: 748: 744: 740: 736: 732: 722: 720: 719:Robert Boltje 716: 710: 708: 689: 673: 669: 650: 634: 630: 626: 622: 618: 614: 610: 606: 602: 598: 594: 590: 586: 582: 578: 574: 570: 566: 562: 558: 554: 535: 519: 509: 507: 503: 498: 496: 492: 488: 484: 480: 462: 457: 453: 444: 440: 439:abelian group 435: 433: 429: 425: 421: 417: 413: 409: 405: 401: 397: 393: 389: 386:and let Char( 385: 381: 371: 369: 365: 361: 343: 339: 330: 312: 308: 285: 281: 275: 271: 267: 264: 261: 253: 249: 245: 240: 237: 233: 229: 225: 221: 217: 207: 205: 201: 197: 193: 189: 185: 175: 172: 164: 153: 150: 146: 143: 139: 136: 132: 129: 125: 122: –  121: 117: 116:Find sources: 110: 106: 100: 99: 94:This article 92: 88: 83: 82: 73: 70: 62: 52: 48: 42: 41: 35: 30: 21: 20: 970: 969:Serge Lang, 965: 924: 880: 866: 861:is a finite 858: 853: 845: 841: 838:non-negative 837: 833: 819: 746: 742: 738: 734: 728: 725:Applications 711: 706: 671: 667: 632: 628: 624: 620: 616: 608: 604: 600: 596: 592: 588: 584: 580: 572: 568: 564: 560: 556: 552: 517: 515: 501: 499: 494: 486: 481:ranges over 478: 445:of the form 436: 431: 427: 423: 419: 415: 411: 407: 403: 395: 387: 384:finite group 379: 377: 367: 363: 359: 328: 251: 247: 243: 241: 231: 227: 223: 219: 213: 187: 183: 182: 167: 158: 148: 141: 134: 127: 115: 103:Please help 98:verification 95: 65: 56: 37: 848:must be a 587:) of Char*( 196:mathematics 51:introducing 984:Categories 949:0991.20005 909:0337.20005 899:0849.20004 873:References 563:) of Char( 300:where the 236:J.A. Green 210:Background 131:newspapers 34:references 883:. Dover. 801:⟩ 795:⟨ 769:⟩ 766:θ 760:θ 757:⟨ 690:ω 651:ω 577:John Tate 536:ω 483:subgroups 454:λ 374:Statement 340:ρ 309:λ 282:ρ 272:λ 268:∑ 202:, within 198:known as 161:July 2024 59:July 2020 787:(where 477:, where 331:and the 854:SL(2,3) 441:) by 402:. Char( 145:scholar 47:improve 947:  937:  907:  897:  887:  747:> 0 729:Using 705:) by | 512:Proofs 147:  140:  133:  126:  118:  36:, but 957:Notes 836:is a 382:be a 152:JSTOR 138:books 935:ISBN 885:ISBN 749:and 378:Let 327:are 124:news 945:Zbl 905:Zbl 895:Zbl 709:|. 485:of 410:of 394:of 246:or 206:. 107:by 986:: 943:. 933:. 893:. 721:. 670:*( 619:*( 605:p. 599:*( 583:*( 497:. 432:G. 228:G. 951:. 901:. 867:G 859:G 846:G 842:G 834:G 798:, 775:1 772:= 763:, 743:G 739:G 707:G 693:] 687:[ 683:Z 672:G 668:I 654:] 648:[ 644:Z 633:G 631:( 629:I 625:G 621:G 617:I 609:G 601:G 597:I 593:p 589:G 585:G 581:I 573:G 571:( 569:I 565:G 561:G 559:( 557:I 553:G 539:] 533:[ 529:Z 518:G 502:H 495:H 487:G 479:H 463:G 458:H 428:G 412:G 404:G 396:G 388:G 380:G 368:L 364:L 360:G 344:i 313:i 286:i 276:i 265:+ 262:1 252:G 232:G 224:G 220:G 174:) 168:( 163:) 159:( 149:· 142:· 135:· 128:· 101:. 72:) 66:( 61:) 57:( 43:.

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"Brauer's theorem on induced characters"
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Richard Brauer
mathematics
character theory
representation theory of a finite group
Artin's induction theorem
J.A. Green
finite group
class functions
irreducible characters
abelian group
induced characters
subgroups
linear characters
Brauer elementary subgroups

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