{"title":"On some generic classes of ergodic measure preserving transformations","authors":"E. Glasner, J. Thouvenot, B. Weiss","doi":"10.1090/mosc/312","DOIUrl":null,"url":null,"abstract":"<p>We answer positively a question of Ryzhikov, namely we show that being a relatively weakly mixing extension is a comeager property in the Polish group of measure preserving transformations. We study some related classes of ergodic transformations and their interrelations. In the second part of the paper we show that for a fixed ergodic <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper T\">\n <mml:semantics>\n <mml:mi>T</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">T</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> with property <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"bold upper A\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"bold\">A</mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathbf {A}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>, a generic extension <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"ModifyingAbove upper T With caret\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mover>\n <mml:mi>T</mml:mi>\n <mml:mo>^<!-- ^ --></mml:mo>\n </mml:mover>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\widehat {T}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper T\">\n <mml:semantics>\n <mml:mi>T</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">T</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> also has property <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"bold upper A\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"bold\">A</mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathbf {A}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. Here <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"bold upper A\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"bold\">A</mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathbf {A}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> stands for each of the following properties: (i) having the same entropy as <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper T\">\n <mml:semantics>\n <mml:mi>T</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">T</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>, (ii) Bernoulli, (iii) K, and (iv) loosely Bernoulli.</p>","PeriodicalId":37924,"journal":{"name":"Transactions of the Moscow Mathematical Society","volume":" ","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2020-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"9","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Transactions of the Moscow Mathematical Society","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1090/mosc/312","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"Mathematics","Score":null,"Total":0}
引用次数: 9
Abstract
We answer positively a question of Ryzhikov, namely we show that being a relatively weakly mixing extension is a comeager property in the Polish group of measure preserving transformations. We study some related classes of ergodic transformations and their interrelations. In the second part of the paper we show that for a fixed ergodic TT with property A\mathbf {A}, a generic extension T^\widehat {T} of TT also has property A\mathbf {A}. Here A\mathbf {A} stands for each of the following properties: (i) having the same entropy as TT, (ii) Bernoulli, (iii) K, and (iv) loosely Bernoulli.