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Talk:Riesz representation theorem

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The first paragraph says: "The theorem is the justification for the bra-ket notation popular in the mathematical treatment of quantum mechanics."... What? I would hardly call it the "justification" for that notation (which can be easily explained in terms of inner products!); nor do I think that some
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This article seems well put together, but it would be nice if there was a "prerequisites" part that said what math courses would be appropriate for understanding the material. Even just an "Undergraduate" or "Graduate" designation would be helpful to minimize the amount of time needed by students to
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is a new editor for WP math articles: if you think you know this material well, and can improve it, then please do so. Just be careful not to wreck the article in the process: us "old timers" find many well-meaning edits to be of questionable value, often muddying or obscuring the subject matter.
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Kolmogorov-Fumin, Rudin), and the dual of L^p being L^q with 1/p+1/q=1 (e.g. Lieb-Loss, Royden). Although the opening text of this page is helpful, I think it would be useful to either have all three discussed on the same page or to have a disambiguation page where all three appear equally.
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There are three (or possibly four) results that are commonly called the "Riesz representation theorem": the dual of a Hilbert space being itself (e.g. Lax, Reed-Simon), the dual of continuous functions being given by appropriate measures (with slightly different results for C_0 and C_c, e.g.
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By the way, I'm not really a new editor of math articles. I'm doing it more frequently now because I'm revising for exams, but also it hasn't been until recently that my browser would keep around the Knowledge cookie for more than a few days, so most of my edits are anonymous.
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Hmm. This article, as currently written, is clear enough if one already knows the subject matter, and one's interest in reading it to "refresh one's memory". But if one does not know Hilbert spaces well, then it appears confusing and poorly structured. I note that
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I think I understand now what the comment is attempting to say. I will move the comment lower down (because the theorem has applications outside of QM), and I will try to clarify it. If there is a problem, please fix rather than just reverting.
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It says, ISMW, that the distinction between real and complex forms is the appearance of the complex conjugation in the complex version. This doesn't fit the definition given for "anti-isomorphism" in the linked article.
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What is the source which says "Hilbert spaces are generally assumed to be complex"? This is not true for all fields of math. Often in, say, numerical analysis, one says Hilbert space rather than real Hilbert space?
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Riesz representation theorem. Another textbook of mine, Funcional Analysis by Michael Reed and Barry Simon, calls the first version the "Riesz lemma". (Disambiguation page is good, though.)
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two very different fonts are used for capital phi. one is hard to distinguish from lower case phi. This could be very confusing for people who don't already know what's going on.
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Those sound fine to me. And the page can always be moved later if you find a canonical name. (Lemma doesn't sound lame to me, but I didn't grow up speaking Spanish.)
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imagined connection to physics is a helpful way to start the article. If anything, the sentence should be reworded and moved to the very bottom.
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Thanks. The edits looked good. I made a minor change. Also, my browser has a "remember me" button which keeps me logged in for weeks at a time.
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Everything, more or less, about Hilbert space can be 'explained in terms of inner products'. I don't see that that invalidates what is said.
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Is the proof of the Riesz-Frechet representation theorem disregarding conjugate linearity? I suppose this works over
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Hmmm. "Riesz lemma" makes the result sound pretty lame (Riesz layma). We could give it a really long name.
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depend on the Riesz representation theorem for? Obviously more needs to be said by way of explanation.
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on Knowledge. If you would like to participate, please visit the project page, where you can join
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This page should be split up into three articles. If there is no objection, I will do this soon.
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Er, not so happy about that. Rudin (Real and Complex Analysis) presents the second version as
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I agree. What would you call the first two sections? The third one has a canonical name,
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is non-zero seems to rely on the Axiom of Choice. One fairly boring proof is via
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I've added a few sentences to the proof explaining that showing that
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Riesz representation theorem for linear functionals on Hilbert spaces
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is non-empty relies on Zorn's Lemma, the Cauchy completeness of
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Should I have used the phrase "trivially explained"? I.e.
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The proof is incomplete because it doesn't show that
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There could also be a disambiguation page called 101:, a collaborative effort to improve the coverage of 938: 918: 898: 853: 811: 791: 771: 745: 698: 649: 496: 462: 416: 290:find books to explain the prerequisite knowledge. 631:conjugate linearity in the proof of Riesz-Frechet 613:Perhaps it should say "anti-isometric" instead? 706:if we want to generalize to the complex case? 241:Riesz representation theorem on Hilbert space 8: 740: 734: 485: 457: 445: 431: 411: 399: 393: 379: 47: 931: 911: 890: 884: 845: 839: 804: 784: 758: 725: 719: 671: 670: 662: 643: 642: 640: 477: 475: 437: 429: 385: 377: 49: 19: 7: 746:{\displaystyle M^{\perp }\neq \{0\}} 699:{\displaystyle f={\bar {\phi (g)}}g} 95:This article is within the scope of 38:It is of interest to the following 497:{\displaystyle |b\rangle \equiv b} 14: 978:Mid-priority mathematics articles 115:Knowledge:WikiProject Mathematics 118:Template:WikiProject Mathematics 82: 72: 51: 20: 135:This article has been rated as 772:{\displaystyle \varphi \neq 0} 687: 683: 677: 600:19:59, 20 September 2013 (UTC) 478: 438: 386: 1: 563:01:18, 28 February 2006 (UTC) 550:20:44, 27 February 2006 (UTC) 538:20:13, 27 February 2006 (UTC) 527:16:15, 26 February 2006 (UTC) 509:18:36, 25 February 2006 (UTC) 364:16:49, 17 February 2006 (UTC) 354:16:34, 17 February 2006 (UTC) 109:and see a list of open tasks. 973:B-Class mathematics articles 956:14:14, 28 January 2021 (UTC) 875:13:43, 28 January 2021 (UTC) 829:09:09, 28 January 2021 (UTC) 650:{\displaystyle \mathbb {R} } 625:02:44, 6 February 2014 (UTC) 187:Riesz representation theorem 306:06:13, 8 January 2007 (UTC) 191:Extension of Radon measures 994: 899:{\displaystyle M^{\perp }} 854:{\displaystyle M^{\perp }} 581:02:20, 28 March 2023 (UTC) 337:17:28, 7 August 2014 (UTC) 166:02:23, 24 Dec 2004 (UTC) 134: 67: 46: 926:, and the continuity of 812:{\displaystyle \varphi } 270:05:50, 24 Dec 2004 (UTC) 247:04:35, 24 Dec 2004 (UTC) 220:04:27, 24 Dec 2004 (UTC) 201:03:53, 24 Dec 2004 (UTC) 178:03:42, 24 Dec 2004 (UTC) 141:project's priority scale 424:. What do the operator 98:WikiProject Mathematics 940: 920: 900: 855: 813: 793: 773: 747: 700: 651: 498: 464: 418: 28:This article is rated 941: 939:{\displaystyle \phi } 921: 901: 856: 814: 799:or the continuity of 794: 774: 748: 701: 652: 499: 465: 419: 296:comment was added by 930: 910: 883: 838: 803: 783: 757: 718: 661: 639: 474: 428: 376: 172:Riesz-Markov theorem 121:mathematics articles 834:The statement that 819:in the argument. -- 710:Proof is incomplete 936: 916: 896: 851: 809: 789: 769: 743: 696: 647: 494: 460: 414: 90:Mathematics portal 34:content assessment 919:{\displaystyle H} 792:{\displaystyle H} 690: 605:Misplaced "anti"? 327:comment added by 309: 155: 154: 151: 150: 147: 146: 985: 945: 943: 942: 937: 925: 923: 922: 917: 905: 903: 902: 897: 895: 894: 860: 858: 857: 852: 850: 849: 818: 816: 815: 810: 798: 796: 795: 790: 778: 776: 775: 770: 752: 750: 749: 744: 730: 729: 705: 703: 702: 697: 692: 691: 686: 672: 657:, but shouldn't 656: 654: 653: 648: 646: 586:minor font issue 503: 501: 500: 495: 481: 469: 467: 466: 461: 441: 423: 421: 420: 415: 389: 361:Charles Matthews 339: 291: 158:Split up article 123: 122: 119: 116: 113: 92: 87: 86: 76: 69: 68: 63: 55: 48: 31: 25: 24: 16: 993: 992: 988: 987: 986: 984: 983: 982: 963: 962: 928: 927: 908: 907: 886: 881: 880: 841: 836: 835: 801: 800: 781: 780: 755: 754: 721: 716: 715: 712: 673: 659: 658: 637: 636: 633: 617:198.228.228.161 607: 588: 472: 471: 470:and the vector 426: 425: 374: 373: 346: 329:129.215.104.198 322: 292:—The preceding 160: 120: 117: 114: 111: 110: 88: 81: 61: 32:on Knowledge's 29: 12: 11: 5: 991: 989: 981: 980: 975: 965: 964: 961: 960: 959: 958: 935: 915: 893: 889: 848: 844: 808: 788: 768: 765: 762: 742: 739: 736: 733: 728: 724: 711: 708: 695: 689: 685: 682: 679: 676: 669: 666: 645: 632: 629: 606: 603: 587: 584: 568: 567: 566: 565: 553: 552: 541: 540: 514: 513: 512: 511: 493: 490: 487: 484: 480: 459: 456: 453: 450: 447: 444: 440: 436: 433: 413: 410: 407: 404: 401: 398: 395: 392: 388: 384: 381: 367: 366: 345: 342: 341: 340: 317: 316: 315: 314: 313: 312: 311: 310: 298:151.203.160.33 280: 279: 278: 277: 276: 275: 274: 273: 272: 271: 255: 254: 253: 252: 251: 250: 249: 248: 226: 225: 224: 223: 222: 221: 205: 204: 203: 202: 195:Riesz theorems 180: 179: 159: 156: 153: 152: 149: 148: 145: 144: 133: 127: 126: 124: 107:the discussion 94: 93: 77: 65: 64: 56: 44: 43: 37: 26: 13: 10: 9: 6: 4: 3: 2: 990: 979: 976: 974: 971: 970: 968: 957: 953: 949: 933: 913: 891: 887: 878: 877: 876: 872: 868: 864: 846: 842: 833: 832: 831: 830: 826: 822: 806: 786: 766: 763: 760: 737: 731: 726: 722: 709: 707: 693: 680: 674: 667: 664: 630: 628: 626: 622: 618: 614: 611: 604: 602: 601: 597: 593: 585: 583: 582: 578: 574: 564: 561: 557: 556: 555: 554: 551: 548: 543: 542: 539: 536: 531: 530: 529: 528: 525: 520: 510: 507: 491: 488: 482: 454: 451: 448: 442: 434: 408: 405: 402: 396: 390: 382: 371: 370: 369: 368: 365: 362: 358: 357: 356: 355: 352: 343: 338: 334: 330: 326: 319: 318: 307: 303: 299: 295: 288: 287: 286: 285: 284: 283: 282: 281: 269: 265: 264: 263: 262: 261: 260: 259: 258: 257: 256: 246: 242: 238: 234: 233: 232: 231: 230: 229: 228: 227: 219: 215: 211: 210: 209: 208: 207: 206: 200: 197:or something. 196: 192: 188: 184: 183: 182: 181: 177: 173: 169: 168: 167: 165: 157: 142: 138: 132: 129: 128: 125: 108: 104: 100: 99: 91: 85: 80: 78: 75: 71: 70: 66: 60: 57: 54: 50: 45: 41: 35: 27: 23: 18: 17: 863:Zorn's lemma 713: 634: 615: 612: 608: 589: 569: 515: 347: 344:Introduction 323:— Preceding 240: 236: 213: 194: 190: 186: 161: 137:Mid-priority 136: 96: 62:Mid‑priority 40:WikiProjects 112:Mathematics 103:mathematics 59:Mathematics 967:Categories 627:Collin237 573:LavaCircus 185:How about 592:Looksurly 325:unsigned 294:unsigned 268:Dbenbenn 218:Dbenbenn 176:Dbenbenn 948:Svennik 867:Svennik 821:Svennik 519:User:A5 139:on the 30:B-class 36:scale. 753:when 560:linas 524:linas 245:CSTAR 199:CSTAR 164:CSTAR 952:talk 871:talk 865:. -- 825:talk 621:talk 596:talk 577:talk 333:talk 302:talk 189:and 239:or 214:the 174:. 131:Mid 969:: 954:) 934:ϕ 892:⊥ 873:) 847:⊥ 827:) 807:φ 764:≠ 761:φ 732:≠ 727:⊥ 688:¯ 675:ϕ 623:) 598:) 579:) 571:-- 547:A5 535:A5 506:A5 489:≡ 486:⟩ 458:⟩ 455:⋅ 446:⟨ 443:≡ 432:⟨ 412:⟩ 400:⟨ 394:⟩ 380:⟨ 351:A5 335:) 304:) 243:. 950:( 914:H 888:M 869:( 843:M 823:( 787:H 767:0 741:} 738:0 735:{ 723:M 694:g 684:) 681:g 678:( 668:= 665:f 644:R 619:( 594:( 575:( 492:b 483:b 479:| 452:, 449:a 439:| 435:a 409:b 406:, 403:a 397:= 391:b 387:| 383:a 331:( 308:. 300:( 143:. 42::

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Riesz-Markov theorem
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151.203.160.33
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129.215.104.198
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17:28, 7 August 2014 (UTC)
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