{"title":"求和μ (n):一个更快的初等算法。","authors":"Harald Andrés Helfgott, Lola Thompson","doi":"10.1007/s40993-022-00408-8","DOIUrl":null,"url":null,"abstract":"<p><p>We present a new elementary algorithm that takes <math><mrow><mtext>time</mtext> <mspace></mspace> <mspace></mspace> <msub><mi>O</mi> <mi>ϵ</mi></msub> <mfenced><msup><mi>x</mi> <mfrac><mn>3</mn> <mn>5</mn></mfrac> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mrow><mfrac><mn>8</mn> <mn>5</mn></mfrac> <mo>+</mo> <mi>ϵ</mi></mrow> </msup> </mfenced> <mspace></mspace> <mspace></mspace> <mtext>and</mtext> <mspace></mspace> <mtext>space</mtext> <mspace></mspace> <mspace></mspace> <mi>O</mi> <mfenced><msup><mi>x</mi> <mfrac><mn>3</mn> <mn>10</mn></mfrac> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mfrac><mn>13</mn> <mn>10</mn></mfrac> </msup> </mfenced> </mrow> </math> (measured bitwise) for computing <math><mrow><mi>M</mi> <mrow><mo>(</mo> <mi>x</mi> <mo>)</mo></mrow> <mo>=</mo> <msub><mo>∑</mo> <mrow><mi>n</mi> <mo>≤</mo> <mi>x</mi></mrow> </msub> <mi>μ</mi> <mrow><mo>(</mo> <mi>n</mi> <mo>)</mo></mrow> <mo>,</mo></mrow> </math> where <math><mrow><mi>μ</mi> <mo>(</mo> <mi>n</mi> <mo>)</mo></mrow> </math> is the Möbius function. This is the first improvement in the exponent of <i>x</i> for an elementary algorithm since 1985. We also show that it is possible to reduce space consumption to <math><mrow><mi>O</mi> <mo>(</mo> <msup><mi>x</mi> <mrow><mn>1</mn> <mo>/</mo> <mn>5</mn></mrow> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mrow><mn>5</mn> <mo>/</mo> <mn>3</mn></mrow> </msup> <mo>)</mo></mrow> </math> by the use of (Helfgott in: Math Comput 89:333-350, 2020), at the cost of letting time rise to the order of <math> <mrow><msup><mi>x</mi> <mrow><mn>3</mn> <mo>/</mo> <mn>5</mn></mrow> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mn>2</mn></msup> <mo>log</mo> <mo>log</mo> <mi>x</mi></mrow> </math> .</p>","PeriodicalId":43826,"journal":{"name":"Research in Number Theory","volume":null,"pages":null},"PeriodicalIF":0.6000,"publicationDate":"2023-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9731940/pdf/","citationCount":"0","resultStr":"{\"title\":\"<ArticleTitle xmlns:ns0=\\\"http://www.w3.org/1998/Math/MathML\\\">Summing <ns0:math><ns0:mrow><ns0:mi>μ</ns0:mi> <ns0:mo>(</ns0:mo> <ns0:mi>n</ns0:mi> <ns0:mo>)</ns0:mo></ns0:mrow> </ns0:math> : a faster elementary algorithm.\",\"authors\":\"Harald Andrés Helfgott, Lola Thompson\",\"doi\":\"10.1007/s40993-022-00408-8\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p><p>We present a new elementary algorithm that takes <math><mrow><mtext>time</mtext> <mspace></mspace> <mspace></mspace> <msub><mi>O</mi> <mi>ϵ</mi></msub> <mfenced><msup><mi>x</mi> <mfrac><mn>3</mn> <mn>5</mn></mfrac> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mrow><mfrac><mn>8</mn> <mn>5</mn></mfrac> <mo>+</mo> <mi>ϵ</mi></mrow> </msup> </mfenced> <mspace></mspace> <mspace></mspace> <mtext>and</mtext> <mspace></mspace> <mtext>space</mtext> <mspace></mspace> <mspace></mspace> <mi>O</mi> <mfenced><msup><mi>x</mi> <mfrac><mn>3</mn> <mn>10</mn></mfrac> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mfrac><mn>13</mn> <mn>10</mn></mfrac> </msup> </mfenced> </mrow> </math> (measured bitwise) for computing <math><mrow><mi>M</mi> <mrow><mo>(</mo> <mi>x</mi> <mo>)</mo></mrow> <mo>=</mo> <msub><mo>∑</mo> <mrow><mi>n</mi> <mo>≤</mo> <mi>x</mi></mrow> </msub> <mi>μ</mi> <mrow><mo>(</mo> <mi>n</mi> <mo>)</mo></mrow> <mo>,</mo></mrow> </math> where <math><mrow><mi>μ</mi> <mo>(</mo> <mi>n</mi> <mo>)</mo></mrow> </math> is the Möbius function. This is the first improvement in the exponent of <i>x</i> for an elementary algorithm since 1985. We also show that it is possible to reduce space consumption to <math><mrow><mi>O</mi> <mo>(</mo> <msup><mi>x</mi> <mrow><mn>1</mn> <mo>/</mo> <mn>5</mn></mrow> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mrow><mn>5</mn> <mo>/</mo> <mn>3</mn></mrow> </msup> <mo>)</mo></mrow> </math> by the use of (Helfgott in: Math Comput 89:333-350, 2020), at the cost of letting time rise to the order of <math> <mrow><msup><mi>x</mi> <mrow><mn>3</mn> <mo>/</mo> <mn>5</mn></mrow> </msup> <msup><mrow><mo>(</mo> <mo>log</mo> <mi>x</mi> <mo>)</mo></mrow> <mn>2</mn></msup> <mo>log</mo> <mo>log</mo> <mi>x</mi></mrow> </math> .</p>\",\"PeriodicalId\":43826,\"journal\":{\"name\":\"Research in Number Theory\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2023-01-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9731940/pdf/\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Research in Number Theory\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1007/s40993-022-00408-8\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Research in Number Theory","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s40993-022-00408-8","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
We present a new elementary algorithm that takes (measured bitwise) for computing where is the Möbius function. This is the first improvement in the exponent of x for an elementary algorithm since 1985. We also show that it is possible to reduce space consumption to by the use of (Helfgott in: Math Comput 89:333-350, 2020), at the cost of letting time rise to the order of .
期刊介绍:
Research in Number Theory is an international, peer-reviewed Hybrid Journal covering the scope of the mathematical disciplines of Number Theory and Arithmetic Geometry. The Mission of the Journal is to publish high-quality original articles that make a significant contribution to these research areas. It will also publish shorter research communications (Letters) covering nascent research in some of the burgeoning areas of number theory research. This journal publishes the highest quality papers in all of the traditional areas of number theory research, and it actively seeks to publish seminal papers in the most emerging and interdisciplinary areas here as well. Research in Number Theory also publishes comprehensive reviews.