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Talk:Weak topology

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867:, since for the topology derived from the usual norm of continuous linear maps between normed spaces, convergence does not mean uniform convergence on the whole space but only on the unit ball - because in the formula for the norm, the supremum is taken on this ball. May-be one could accept this expression due to the fact that uniform convergence on the whole space would mean for linear maps the same as with discrete topology. But a warning seems to be needed. Moreover this still could create confusion in contexts where also non linear maps are discussed ... 84: 74: 53: 22: 895: 388:
If the weak topology and the initial topology are the same thing, the correct solution is not to delete the redundant information from this article in favor of making the reader follow a link to read another article about the same thing. The correct solution is to merge the two articles. For now, I
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is a priori a function space and so the topology of pointwise convergence is meant. If there really is a general definition of "weak star topology" for non-reflexive spaces, then someone should write it in this section. If there isn't and all we have is the case of function spaces, then the section
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Depends on who you are; to a topologist the topological meaning is probably the usual one. When there is more than one context for a specific title, it seems appropriate to link to the most general context applicable. We can put a note at the top of the initial topology page pointing here for
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Actually, I see now that the information about what the weak topology does is still made clear in the second paragraph. I retract my complaint about the removal of that information. We don't need it twice in the same article, right?
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What I'm about to say has been alluded to many times above, but with insufficient force. In topology and analysis, strong and weak do not merely mean different things, but opposite things, and the article should really reflect that.
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This article calls "strong topology" to what I think it should be called "norm topology", since "strong topology" has a different meaning for spaces of operators between normed spaces, which are of course normed spaces themselves.
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In mathematics, the weak topology on a set, with respect to a collection of functions from that set into topological spaces, is the weakest (that is, smallest or coarsest) topology on the set which makes all the functions
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think the article suffers for clarity by not mentioning what exactly the weak topology "does". A brief definition of terms which may not be known is usual, even if that information is duplicated in that term's article. -
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The quoted theorem says 3.10 Theorem Suppose X is a vector space and X' is a separating vector space of linear functionals on X. Then the X'-topology tau' makes X into a locally convex space whose dual space is X'.
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is ok for the moment and should remain at this level of abstraction, as many people (e.g. physicists) need only this watered down version, so it deserves its own article. I propose the following renaming
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The statement in this article is: If Y is a vector space of linear functionals on X, then the continuous dual of X with respect to the topology σ(X,Y) is precisely equal to Y.(Rudin 1991, Theorem 3.10)
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Any article that delves into the mathematical formalism of the weak topology without stating what the open sets of this topology are, or at least a base for the open sets, or at the very least a
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is certainly used in this sense. But there's no need to duplicate the definition of initial topology in this article, so I've modified the introduction to direct readers to the
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There is a false belief about Knowledge mathematics articles, namely that as long as they are not mathematically incorrect, that is the only criterion for being "good".
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I have trouble understanding how anyone could imagine writing such an article without about a topology without stating at least a subbase for the open sets.
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Quick question: is there any reason for the author(s) of the subsection "Weak-* convergence" to switch back and forth between \phi and \varphi?
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No. It is essential that they explain their subject matter the way you would explain it to a friend who wants to learn about the subject.
729:, which some call a weak topology. Given the variety of meanings "weak topology" can take, I'd be in favour of disambiguating it, as with 706: 320:
should be replaced by a diskussion of pointwise convergence (meaning: delete the false definition and only use the following section).
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Problems: So first of all, it is missing the assumption that Y is separating points which is important for this theorem to hold.
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They're not really different things though, are they? The same thing in two different contexts, one general, one specific. -
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Yes, there's no reason to have it twice. Merging the articles is not a good idea, since they are about different things: the
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Given the variety of meanings and the potential for confusion I think a disambiguation page would really be best here. --
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But the functional analysis meaning is the usual one, so redirecting it to some other article doesn't make much sense. --
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is an isometric isomorphism an the initial topology with respect to it therefore produces the norm topology on
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Secondly it seems like the tau' topology is actually the weak topology on X' and not the weak topology on X.
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article is about the weak topology of a normed vector space and the weak* topology of its dual, while the
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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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Weak topology (on a normed vector space) is just a simple example of the more general concept of
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continuous. Thus although weak topology is an example of initial topology, strong topology is
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I think there is some confusion. The strong topology as used in functional analysis is not a
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Not far, far down in the article, but right where the topology is first described.
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Knowledge:Redirects for discussion/Log/2023 October 29 § Weak compactness
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is used in a wider context than that of functional analysis to mean the
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should not be renamed and we could put a disambiguation article at
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article is about the general concept of initial topologies. --
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The current definition of the weak star topology is wrong. If
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is the strongest topology on X to make a set of functions X→R
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I know the terminology "weak-*-topology" only in cases where
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Some topology textbooks (such as the book by Willard) use
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Bounded weak topology is described in German wikipedia:
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Is this a mistake or do some people really refer to the
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to determine whether its use and function meets the
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Similar considerations apply to 335:Weak topology vs. initial topology 14: 978:Mid-priority mathematics articles 934:Theorem from Rudin wrongly quoted 115:Knowledge:WikiProject Mathematics 893: 118:Template:WikiProject Mathematics 82: 72: 51: 20: 918:until a consensus is reached. 578:an example of final topology. 532:purposes of disambiguation. -- 135:This article has been rated as 654:weak topology (polar topology) 642:weak topology (polar topology) 609:weak topology (polar topology) 473:are also specific examples of 250: 1: 765:16:40, 17 December 2007 (UTC) 747:15:05, 17 December 2007 (UTC) 725:is actually an example of an 715:05:08, 14 December 2007 (UTC) 648:(example of initial topology) 330:19:33, 21 November 2010 (UTC) 269:{\displaystyle T:X\to X^{**}} 109:and see a list of open tasks. 973:C-Class mathematics articles 929:20:51, 29 October 2023 (UTC) 613:locally convex vector spaces 551:to make a set of functions 234:is a reflexive space, then 994: 877:10:25, 31 March 2023 (UTC) 638:(example of weak topology) 559:(a linear subspace of the 513:or something similiar. -- 397:19:23, May 30, 2005 (UTC) 959:08:21, 30 July 2024 (UTC) 854:23:08, 9 April 2021 (UTC) 822:Exceptionally bad article 790:21:01, 4 April 2015 (UTC) 600:21:13, 12 June 2006 (UTC) 536:18:55, 2005 May 31 (UTC) 517:15:22, 2005 May 31 (UTC) 450:18:19, May 31, 2005 (UTC) 410:19:26, May 30, 2005 (UTC) 366:13:03, 30 Apr 2005 (UTC) 189:15:08, 22 Feb 2004 (UTC) 134: 67: 46: 906:redirects for discussion 888:Redirects for discussion 816:17:20, 29 May 2015 (UTC) 723:strong operator topology 694:20:30, 2005 May 31 (UTC) 669:19:49, 31 May 2005 (UTC) 526:18:41, 31 May 2005 (UTC) 482:18:41, 31 May 2005 (UTC) 430:20:02, 30 May 2005 (UTC) 383:08:37, 30 May 2005 (UTC) 205:23:26, 22 Feb 2004 (UTC) 141:project's priority scale 178:11:25, 9 May 2016 (UTC) 98:WikiProject Mathematics 313: 290: 270: 228: 28:This article is rated 773:Bounded weak topology 591:Wouldn't that be the 314: 291: 271: 229: 303: 280: 238: 218: 121:mathematics articles 910:redirect guidelines 904:has been listed at 378:article instead. -- 735:ultraweak topology 309: 286: 266: 224: 210:Weak star topology 197:isn't the same as 193:I don't think so. 90:Mathematics portal 34:content assessment 818: 806:comment added by 717: 705:comment added by 593:discrete topology 471:subspace topology 312:{\displaystyle X} 289:{\displaystyle X} 227:{\displaystyle X} 180: 168:comment added by 155: 154: 151: 150: 147: 146: 985: 903: 901:Weak compactness 897: 884:Weak compactness 737:easier to find. 727:initial topology 700: 588:... continuous." 507:initial topology 499:initial topology 475:initial topology 467:product topology 423:initial topology 376:initial topology 352:initial topology 318: 316: 315: 310: 295: 293: 292: 287: 275: 273: 272: 267: 265: 264: 233: 231: 230: 225: 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: 936: 899: 891: 861: 824: 797: 782:Boris Tsirelson 775: 731:strong topology 688:strong topology 676:strong topology 662:strong topology 356:strong topology 337: 301: 300: 278: 277: 253: 236: 235: 216: 215: 212: 195:Weaker topology 160: 120: 117: 114: 111: 110: 88: 81: 61: 32:on Knowledge's 29: 12: 11: 5: 991: 989: 981: 980: 975: 965: 964: 935: 932: 890: 880: 860: 857: 823: 820: 796: 793: 774: 771: 770: 769: 768: 767: 750: 749: 696: 695: 680:final topology 650: 649: 639: 605: 604: 603: 602: 589: 561:algebraic dual 541:final topology 529: 528: 491: 490: 489: 488: 487: 486: 485: 484: 456: 455: 454: 453: 452: 451: 435: 434: 433: 432: 412: 411: 386: 385: 360:final topology 348: 347: 336: 333: 308: 285: 263: 260: 256: 252: 249: 246: 243: 223: 211: 208: 207: 206: 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: 961: 960: 956: 952: 947: 944: 940: 933: 931: 930: 927: 924: 921: 917: 916: 911: 907: 902: 898:The 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Index


content assessment
WikiProjects
WikiProject icon
Mathematics
WikiProject icon
icon
Mathematics portal
WikiProject Mathematics
mathematics
the discussion
Mid
project's priority scale
unsigned
2001:638:502:A006:213:72FF:FE9F:2852
talk
11:25, 9 May 2016 (UTC)
Tosha
Lupin
78.53.90.64
talk
19:33, 21 November 2010 (UTC)
initial topology
strong topology
final topology
MathMartin
initial topology
Zundark
08:37, 30 May 2005 (UTC)
Lethe

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