{"title":"大多数数字都不正常","authors":"ANDREA AVENI, PAOLO LEONETTI","doi":"10.1017/s0305004122000469","DOIUrl":null,"url":null,"abstract":"<p>We show, from a topological viewpoint, that most numbers are not normal in a strong sense. More precisely, the set of numbers <span>\n<span>\n<img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20230612115128646-0745:S0305004122000469:S0305004122000469_inline1.png\"/>\n<span data-mathjax-type=\"texmath\"><span>\n$x \\in (0,1]$\n</span></span>\n</span>\n</span> with the following property is comeager: for all integers <span>\n<span>\n<img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20230612115128646-0745:S0305004122000469:S0305004122000469_inline2.png\"/>\n<span data-mathjax-type=\"texmath\"><span>\n$b\\ge 2$\n</span></span>\n</span>\n</span> and <span>\n<span>\n<img data-mimesubtype=\"png\" data-type=\"\" src=\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20230612115128646-0745:S0305004122000469:S0305004122000469_inline3.png\"/>\n<span data-mathjax-type=\"texmath\"><span>\n$k\\ge 1$\n</span></span>\n</span>\n</span>, the sequence of vectors made by the frequencies of all possibile strings of length <span>k</span> in the <span>b</span>-adic representation of <span>x</span> has a maximal subset of accumulation points, and each of them is the limit of a subsequence with an index set of nonzero asymptotic density. This extends and provides a streamlined proof of the main result given by Olsen (2004) in this Journal. We provide analogues in the context of analytic P-ideals and regular matrices.</p>","PeriodicalId":18320,"journal":{"name":"Mathematical Proceedings of the Cambridge Philosophical Society","volume":null,"pages":null},"PeriodicalIF":0.6000,"publicationDate":"2022-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Most numbers are not normal\",\"authors\":\"ANDREA AVENI, PAOLO LEONETTI\",\"doi\":\"10.1017/s0305004122000469\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>We show, from a topological viewpoint, that most numbers are not normal in a strong sense. More precisely, the set of numbers <span>\\n<span>\\n<img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20230612115128646-0745:S0305004122000469:S0305004122000469_inline1.png\\\"/>\\n<span data-mathjax-type=\\\"texmath\\\"><span>\\n$x \\\\in (0,1]$\\n</span></span>\\n</span>\\n</span> with the following property is comeager: for all integers <span>\\n<span>\\n<img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20230612115128646-0745:S0305004122000469:S0305004122000469_inline2.png\\\"/>\\n<span data-mathjax-type=\\\"texmath\\\"><span>\\n$b\\\\ge 2$\\n</span></span>\\n</span>\\n</span> and <span>\\n<span>\\n<img data-mimesubtype=\\\"png\\\" data-type=\\\"\\\" src=\\\"https://static.cambridge.org/binary/version/id/urn:cambridge.org:id:binary:20230612115128646-0745:S0305004122000469:S0305004122000469_inline3.png\\\"/>\\n<span data-mathjax-type=\\\"texmath\\\"><span>\\n$k\\\\ge 1$\\n</span></span>\\n</span>\\n</span>, the sequence of vectors made by the frequencies of all possibile strings of length <span>k</span> in the <span>b</span>-adic representation of <span>x</span> has a maximal subset of accumulation points, and each of them is the limit of a subsequence with an index set of nonzero asymptotic density. This extends and provides a streamlined proof of the main result given by Olsen (2004) in this Journal. 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We show, from a topological viewpoint, that most numbers are not normal in a strong sense. More precisely, the set of numbers
$x \in (0,1]$
with the following property is comeager: for all integers
$b\ge 2$
and
$k\ge 1$
, the sequence of vectors made by the frequencies of all possibile strings of length k in the b-adic representation of x has a maximal subset of accumulation points, and each of them is the limit of a subsequence with an index set of nonzero asymptotic density. This extends and provides a streamlined proof of the main result given by Olsen (2004) in this Journal. We provide analogues in the context of analytic P-ideals and regular matrices.
期刊介绍:
Papers which advance knowledge of mathematics, either pure or applied, will be considered by the Editorial Committee. The work must be original and not submitted to another journal.