{"title":"Radon–Nikodým property and Lau’s conjecture","authors":"Andrzej Wiśnicki","doi":"10.1090/proc/16884","DOIUrl":null,"url":null,"abstract":"<p>There is a long-standing problem, posed by A.T.-M. Lau [<italic>Fixed point theory and its applications</italic>, Academic Press, New York-London, 1976, pp. 121–129], whether left amenability is sufficient to ensure the existence of a common fixed point for every jointly weak<inline-formula content-type=\"math/mathml\"> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"Superscript asterisk\"> <mml:semantics> <mml:msup> <mml:mi/> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msup> <mml:annotation encoding=\"application/x-tex\">^{\\ast }</mml:annotation> </mml:semantics> </mml:math> </inline-formula> continuous nonexpansive semigroup action on a nonempty weak<inline-formula content-type=\"math/mathml\"> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"Superscript asterisk\"> <mml:semantics> <mml:msup> <mml:mi/> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msup> <mml:annotation encoding=\"application/x-tex\">^{\\ast }</mml:annotation> </mml:semantics> </mml:math> </inline-formula> compact convex set in a dual Banach space. In this note we discuss the current status of this problem and give a partial solution in the case of weak<inline-formula content-type=\"math/mathml\"> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"Superscript asterisk\"> <mml:semantics> <mml:msup> <mml:mi/> <mml:mrow> <mml:mo>∗</mml:mo> </mml:mrow> </mml:msup> <mml:annotation encoding=\"application/x-tex\">^{\\ast }</mml:annotation> </mml:semantics> </mml:math> </inline-formula> compact convex sets with the Radon–Nikodým property.</p>","PeriodicalId":20696,"journal":{"name":"Proceedings of the American Mathematical Society","volume":"68 1","pages":""},"PeriodicalIF":0.8000,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Proceedings of the American Mathematical Society","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1090/proc/16884","RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATHEMATICS","Score":null,"Total":0}
引用次数: 0
Abstract
There is a long-standing problem, posed by A.T.-M. Lau [Fixed point theory and its applications, Academic Press, New York-London, 1976, pp. 121–129], whether left amenability is sufficient to ensure the existence of a common fixed point for every jointly weak∗^{\ast } continuous nonexpansive semigroup action on a nonempty weak∗^{\ast } compact convex set in a dual Banach space. In this note we discuss the current status of this problem and give a partial solution in the case of weak∗^{\ast } compact convex sets with the Radon–Nikodým property.
A.T.-M. Lau [Fixed point theory and its applications, Academic Press, New York-London, 1976, pp.Lau [Fixed point theory and its applications, Academic Press, New York-London, 1976, pp.在本论文中,我们讨论了这一问题的现状,并给出了具有 Radon-Nikodým 性质的弱∗ ^{\ast } 紧凑凸集的部分解决方案。
期刊介绍:
All articles submitted to this journal are peer-reviewed. The AMS has a single blind peer-review process in which the reviewers know who the authors of the manuscript are, but the authors do not have access to the information on who the peer reviewers are.
This journal is devoted to shorter research articles (not to exceed 15 printed pages) in all areas of pure and applied mathematics. To be published in the Proceedings, a paper must be correct, new, and significant. Further, it must be well written and of interest to a substantial number of mathematicians. Piecemeal results, such as an inconclusive step toward an unproved major theorem or a minor variation on a known result, are in general not acceptable for publication. Longer papers may be submitted to the Transactions of the American Mathematical Society. Published pages are the same size as those generated in the style files provided for AMS-LaTeX.