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Coherent set of characters

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177:
Feit proved several theorems giving conditions under which a set of characters is coherent. A typical one is as follows. Suppose that
492: 165:) is non-zero. Although strictly speaking coherence is really a property of the isometry Ď„, it is common to say that the set 32:
from the degree-zero subspace of a space of characters to the whole space. The general notion of coherence was developed by
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1960 Institute on Finite Groups: Held at California Institute of Technology, Pasadena, California, August 1-August 28, 1960
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is the Sylow 2-subgroup and Ď„ is induction, then coherence fails for the second reason. The abelianization of
484: 410: 57: 598: 476: 403: 85: 49: 44:), as a generalization of the proof by Frobenius of the existence of a Frobenius kernel of a 17: 582: 533: 502: 465: 364:
In the proof of the Frobenius theory about the existence of a kernel of a Frobenius group
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In more complicated cases the isometry Ď„ is no longer induction. For example, in the
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is a Sylow 2-subgroup, with Ď„ induction, then coherence fails for the first reason:
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acts simply transitively on its non-identity elements (in which case
29: 56:, Chapter 3) developed coherence further in the proof of the 483:, Proc. Sympos. Pure Math., vol. VI, Providence, R.I.: 212:
in their kernel. Suppose that Ď„ is a linear isometry from
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is the simple Suzuki group of order (2–1) 2( 2+1) with
432:"On a class of doubly transitive permutation groups" 325:has order 2–1 and acts simply transitively on it. 169:is coherent instead of saying that Ď„ is coherent. 100:) for the set of integral linear combinations of 590: 391:) is just induction, although its extension to 539: 518:, W. A. Benjamin, Inc., New York-Amsterdam, 376:is the set of all irreducible characters of 53: 477:"Group characters. Exceptional characters" 142:if it can be extended to an isometry from 564: 447: 269:whose abelianization has order at most 4| 115:) for the subset of degree 0 elements of 134:) to the degree 0 virtual characters of 48:and of the work of Brauer and Suzuki on 591: 123:). Suppose that Ď„ is an isometry from 549:"Solvability of groups of odd order" 508: 471: 426: 41: 37: 406:the isometry Ď„ is again induction. 372:is the subgroup fixing a point and 235:is an elementary abelian group and 13: 223:) into the degree 0 characters of 14: 615: 204:be the irreducible characters of 196:is a Frobenius group with kernel 172: 76:is a subgroup of a finite group 436:Illinois Journal of Mathematics 553:Pacific Journal of Mathematics 1: 485:American Mathematical Society 420: 359: 348:has order 2, while the group 227:. Then Ď„ is coherent unless 67: 28:that allows one to extend an 7: 515:Characters of finite groups 479:, in Hall, Marshall (ed.), 402:Similarly in the theory of 281: 64:of odd order are solvable. 10: 620: 181:is a subgroup of a group 54:Feit & Thompson (1963 24:is a property of sets of 566:10.2140/pjm.1963.13.775 449:10.1215/ijm/1255455862 413:the isometry Ď„ is the 404:exceptional characters 290:is the simple group SL 265:-group for some prime 86:irreducible characters 50:exceptional characters 604:Representation theory 411:Feit–Thompson theorem 58:Feit–Thompson theorem 18:representation theory 399:) is not induction. 380:, the isometry Ď„ on 368:where the subgroup 150:) to characters of 138:. Then Ď„ is called 487:, pp. 67–70, 315:elementary abelian 545:Thompson, John G. 494:978-0-8218-1406-2 261:is a non-abelian 208:that do not have 611: 585: 568: 536: 505: 468: 451: 16:In mathematical 619: 618: 614: 613: 612: 610: 609: 608: 589: 588: 526: 495: 423: 386: 362: 356:has order 2–1. 300: 293: 284: 249: 218: 175: 160: 129: 110: 70: 46:Frobenius group 12: 11: 5: 617: 607: 606: 601: 587: 586: 537: 524: 506: 493: 469: 442:(2): 170–186, 422: 419: 384: 361: 358: 298: 291: 283: 280: 279: 278: 255: 247: 216: 174: 173:Feit's theorem 171: 158: 127: 108: 69: 66: 9: 6: 4: 3: 2: 616: 605: 602: 600: 599:Finite groups 597: 596: 594: 584: 580: 576: 572: 567: 562: 558: 554: 550: 546: 542: 538: 535: 531: 527: 525:9780805324341 521: 517: 516: 511: 507: 504: 500: 496: 490: 486: 482: 478: 474: 470: 467: 463: 459: 455: 450: 445: 441: 437: 433: 429: 425: 424: 418: 416: 415:Dade isometry 412: 407: 405: 400: 398: 394: 390: 383: 379: 375: 371: 367: 357: 355: 351: 347: 343: 339: 335: 331: 326: 324: 320: 316: 312: 308: 304: 297: 289: 276: 272: 268: 264: 260: 256: 253: 246: 242: 238: 234: 230: 229: 228: 226: 222: 215: 211: 207: 203: 199: 195: 191: 188: 184: 180: 170: 168: 164: 157: 153: 149: 145: 141: 137: 133: 126: 122: 118: 114: 107: 103: 99: 95: 91: 87: 83: 79: 75: 72:Suppose that 65: 63: 59: 55: 51: 47: 43: 39: 35: 31: 27: 23: 19: 559:: 775–1029, 556: 552: 541:Feit, Walter 514: 510:Feit, Walter 480: 473:Feit, Walter 439: 435: 428:Feit, Walter 408: 401: 396: 392: 388: 381: 377: 373: 369: 365: 363: 353: 349: 345: 341: 337: 333: 329: 327: 322: 318: 310: 306: 302: 295: 287: 285: 274: 270: 266: 262: 258: 251: 244: 240: 236: 232: 224: 220: 213: 209: 205: 201: 197: 193: 192:, such that 189: 182: 178: 176: 166: 162: 155: 151: 147: 143: 139: 135: 131: 124: 120: 116: 112: 105: 101: 97: 93: 89: 81: 77: 73: 71: 21: 15: 593:Categories 421:References 340:>1 and 305:>1 and 254:) is zero) 200:, and let 187:normalizer 68:Definition 26:characters 575:0030-8730 458:0019-2082 84:a set of 60:that all 22:coherence 547:(1963), 512:(1967), 475:(1962), 430:(1960), 360:Examples 336:odd and 282:Examples 140:coherent 92:. Write 30:isometry 583:0166261 534:0219636 503:0132779 466:0113953 231:either 36: ( 581:  573:  532:  522:  501:  491:  464:  456:  301:) for 104:, and 80:, and 62:groups 185:with 571:ISSN 520:ISBN 489:ISBN 454:ISSN 317:and 277:|+1. 154:and 42:1962 38:1960 34:Feit 561:doi 444:doi 328:If 313:is 286:If 257:or 88:of 595:: 579:MR 577:, 569:, 557:13 555:, 551:, 543:; 530:MR 528:, 499:MR 497:, 462:MR 460:, 452:, 438:, 434:, 417:. 52:. 40:, 20:, 563:: 446:: 440:4 397:S 395:( 393:I 389:S 387:( 385:0 382:I 378:H 374:S 370:H 366:G 354:H 352:/ 350:N 346:H 342:H 338:n 334:n 330:G 323:H 321:/ 319:N 311:H 307:H 303:n 299:2 296:F 294:( 292:2 288:G 275:H 273:/ 271:N 267:p 263:p 259:H 252:S 250:( 248:0 245:I 241:H 239:/ 237:N 233:H 225:G 221:S 219:( 217:0 214:I 210:H 206:N 202:S 198:H 194:N 190:N 183:G 179:H 167:S 163:S 161:( 159:0 156:I 152:G 148:S 146:( 144:I 136:G 132:S 130:( 128:0 125:I 121:S 119:( 117:I 113:S 111:( 109:0 106:I 102:S 98:S 96:( 94:I 90:H 82:S 78:G 74:H

Index

representation theory
characters
isometry
Feit
1960
1962
Frobenius group
exceptional characters
Feit & Thompson (1963
Feit–Thompson theorem
groups
irreducible characters
normalizer
elementary abelian
exceptional characters
Feit–Thompson theorem
Dade isometry
Feit, Walter
"On a class of doubly transitive permutation groups"
doi
10.1215/ijm/1255455862
ISSN
0019-2082
MR
0113953
Feit, Walter
"Group characters. Exceptional characters"
American Mathematical Society
ISBN
978-0-8218-1406-2

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