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Approximation in algebraic groups

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proved strong approximation for some classical groups. Strong approximation was established in the 1960s and 1970s, for semisimple simply-connected algebraic groups over
605: 682: 525: 386: 490:"Allgemeine Kongruenzklasseneinteilungen der Ideale einfacher Algebren über algebraischen Zahlkörpern und ihre L-Reihen." 113: 568:
Platonov, V. P. (1969), "The problem of strong approximation and the Kneser–Tits hypothesis for algebraic groups",
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Algebraic groups and number theory. (Translated from the 1991 Russian original by Rachel Rowen.)
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Algebraic Groups and Discontinuous Subgroups (Proc. Sympos. Pure Math., Boulder, Colo., 1965)
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Prasad, Gopal (1977), "Strong approximation for semi-simple groups over function fields",
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Margulis, G. A. (1977), "Cobounded subgroups in algebraic groups over local fields",
455: 69: 358: 101: 89: 85: 65: 61: 43: 600:, Pure and Applied Mathematics, vol. 139, Boston, MA: Academic Press, Inc., 109: 505: 459: 645: 581: 553: 513: 393: 251:-rational, then it satisfies weak approximation with respect to any set 653: 108:). In the number field case Platonov also proved a related result over 637: 454:
Weak approximation holds for a broader class of groups, including
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Akademija Nauk SSSR. Funkcional'nyi Analiz i ego Priloženija
373:, p.188) states that a non-solvable linear algebraic group 404:
is simply connected, and each almost simple component
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is an algebraic number field then any connected group
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Izvestiya Akademii Nauk SSSR. Seriya Matematicheskaya
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satisfies weak approximation with respect to the set
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satisfies weak approximation with respect to any set
440:The proofs of strong approximation depended on the 329:) has dense image, or equivalently whether the set 259:, p.402). More generally, for any connected group 284: 256: 128:be a linear algebraic group over a global field 520:Kneser, Martin (1966), "Strong approximation", 494:Journal für die Reine und Angewandte Mathematik 444:for algebraic groups, which for groups of type 596:Platonov, Vladimir; Rapinchuk, Andrei (1994), 369:). The main theorem of strong approximation ( 8: 381:has strong approximation for the finite set 313:approximation is whether the embedding of 222:approximation is whether the embedding of 97: 81: 18:Strong approximation in algebraic groups 144:is a non-empty finite set of places of 57: 370: 105: 73: 451:was only proved several years later. 7: 165:for the product of the completions 25: 120:Formal definitions and properties 243:) has dense image. If the group 1: 526:American Mathematical Society 285:Platonov & Rapinchuk 1994 257:Platonov & Rapinchuk 1994 416:has a non-compact component 287:, p.415). In particular, if 27:In algebraic group theory, 699: 506:10.1515/crll.1938.179.227 476:Superstrong approximation 33:Chinese remainder theorem 488:Eichler, Martin (1938), 263:, there is a finite set 31:are an extension of the 309:The question asked in 279:that is disjoint with 218:The question asked in 114:Kneser–Tits conjecture 29:approximation theorems 625:Annals of Mathematics 683:Diophantine geometry 528:, pp. 187–196, 524:, Providence, R.I.: 377:over a global field 306:of infinite places. 267:of finite places of 182:. For any choice of 385:if and only if its 178:in the finite set 136:the adele ring of 64:. The results for 628:, Second Series, 247:is connected and 16:(Redirected from 690: 678:Algebraic groups 664: 618: 592: 564: 548:(2): 45–57, 95, 536: 516: 464:Chevalley groups 152:for the ring of 148:, then we write 37:algebraic groups 21: 698: 697: 693: 692: 691: 689: 688: 687: 668: 667: 638:10.2307/1970924 621: 608: 595: 567: 539: 519: 487: 484: 472: 450: 442:Hasse principle 424: 352: 305: 242: 206: 173: 164: 122: 55: 23: 22: 15: 12: 11: 5: 696: 694: 686: 685: 680: 670: 669: 666: 665: 632:(3): 553–572, 619: 606: 593: 565: 537: 517: 483: 480: 479: 478: 471: 468: 456:adjoint groups 448: 433:(depending on 420: 355: 354: 348: 303: 238: 202: 169: 160: 121: 118: 86:function field 58:Eichler (1938) 54: 51: 24: 14: 13: 10: 9: 6: 4: 3: 2: 695: 684: 681: 679: 676: 675: 673: 663: 659: 655: 651: 647: 643: 639: 635: 631: 627: 626: 620: 617: 613: 609: 607:0-12-558180-7 603: 599: 594: 591: 587: 583: 579: 576:: 1211–1219, 575: 571: 566: 563: 559: 555: 551: 547: 543: 538: 535: 531: 527: 523: 518: 515: 511: 507: 503: 499: 496:(in German), 495: 491: 486: 485: 481: 477: 474: 473: 469: 467: 465: 461: 457: 452: 447: 443: 438: 436: 432: 428: 423: 419: 415: 411: 407: 403: 399: 395: 391: 388: 384: 380: 376: 372: 368: 364: 360: 351: 347: 343: 339: 335: 332: 331: 330: 328: 324: 320: 316: 312: 307: 302: 298: 294: 290: 286: 282: 278: 274: 270: 266: 262: 258: 254: 250: 246: 241: 237: 233: 229: 225: 221: 216: 214: 210: 205: 201: 197: 193: 189: 185: 181: 177: 172: 168: 163: 159: 155: 151: 147: 143: 139: 135: 131: 127: 119: 117: 115: 111: 107: 103: 99: 95: 91: 90:finite fields 87: 83: 79: 75: 71: 67: 66:number fields 63: 62:global fields 59: 52: 50: 48: 45: 44:global fields 41: 38: 34: 30: 19: 629: 623: 597: 573: 569: 545: 541: 521: 497: 493: 453: 445: 439: 434: 430: 426: 421: 417: 413: 409: 405: 401: 397: 389: 382: 378: 374: 366: 362: 359:dense subset 356: 349: 345: 341: 337: 333: 326: 322: 318: 314: 310: 308: 300: 296: 292: 288: 280: 276: 272: 268: 264: 260: 252: 248: 244: 239: 235: 231: 227: 223: 219: 217: 212: 208: 203: 199: 195: 194:) embeds in 191: 187: 183: 179: 175: 170: 166: 161: 157: 156:-adeles and 153: 149: 145: 141: 137: 133: 129: 125: 123: 110:local fields 92:, is due to 56: 46: 39: 28: 26: 500:: 227–251, 460:inner forms 371:Kneser 1966 112:called the 88:case, over 68:are due to 672:Categories 482:References 271:such that 646:0003-486X 582:0373-2436 554:0374-1990 514:0075-4102 425:for some 394:unipotent 470:See also 94:Margulis 78:Platonov 662:0444571 654:1970924 616:1278263 590:0258839 562:0442107 534:0213361 387:radical 104: ( 96: ( 84:); the 80: ( 72: ( 53:History 660:  652:  644:  614:  604:  588:  580:  560:  552:  532:  512:  311:strong 207:) and 174:, for 132:, and 102:Prasad 100:) and 76:) and 70:Kneser 650:JSTOR 357:is a 321:) in 230:) in 140:. If 42:over 642:ISSN 602:ISBN 578:ISSN 550:ISSN 510:ISSN 458:and 220:weak 124:Let 106:1977 98:1977 82:1969 74:1966 634:doi 630:105 502:doi 498:179 462:of 437:). 429:in 408:of 392:is 361:in 215:). 35:to 674:: 658:MR 656:, 648:, 640:, 612:MR 610:, 586:MR 584:, 574:33 572:, 558:MR 556:, 546:11 544:, 530:MR 508:, 492:, 396:, 299:= 186:, 116:. 49:. 636:: 504:: 449:8 446:E 435:H 431:S 427:s 422:s 418:H 414:N 412:/ 410:G 406:H 402:N 400:/ 398:G 390:N 383:S 379:k 375:G 367:A 365:( 363:G 353:) 350:S 346:A 344:( 342:G 340:) 338:k 336:( 334:G 327:A 325:( 323:G 319:k 317:( 315:G 304:∞ 301:S 297:S 293:G 289:k 283:( 281:T 277:S 273:G 269:k 265:T 261:G 255:( 253:S 249:k 245:G 240:S 236:A 234:( 232:G 228:k 226:( 224:G 213:A 211:( 209:G 204:S 200:A 198:( 196:G 192:k 190:( 188:G 184:S 180:S 176:s 171:s 167:k 162:S 158:A 154:S 150:A 146:k 142:S 138:k 134:A 130:k 126:G 47:k 40:G 20:)

Index

Strong approximation in algebraic groups
Chinese remainder theorem
algebraic groups
global fields
Eichler (1938)
global fields
number fields
Kneser
1966
Platonov
1969
function field
finite fields
Margulis
1977
Prasad
1977
local fields
Kneser–Tits conjecture
Platonov & Rapinchuk 1994
Platonov & Rapinchuk 1994
dense subset
Kneser 1966
radical
unipotent
Hasse principle
adjoint groups
inner forms
Chevalley groups
Superstrong approximation

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