{"title":"On Floer minimal knots in sutured manifolds","authors":"Zhenkun Li, Yi Xie, Boyu Zhang","doi":"10.1090/btran/105","DOIUrl":null,"url":null,"abstract":"<p>Suppose <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"left-parenthesis upper M comma gamma right-parenthesis\">\n <mml:semantics>\n <mml:mrow>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mi>M</mml:mi>\n <mml:mo>,</mml:mo>\n <mml:mi>γ<!-- γ --></mml:mi>\n <mml:mo stretchy=\"false\">)</mml:mo>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">(M, \\gamma )</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is a balanced sutured manifold and <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper K\">\n <mml:semantics>\n <mml:mi>K</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">K</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is a rationally null-homologous knot in <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper M\">\n <mml:semantics>\n <mml:mi>M</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">M</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. It is known that the rank of the sutured Floer homology of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper M minus upper N left-parenthesis upper K right-parenthesis\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>M</mml:mi>\n <mml:mi class=\"MJX-variant\" mathvariant=\"normal\">∖<!-- ∖ --></mml:mi>\n <mml:mi>N</mml:mi>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mi>K</mml:mi>\n <mml:mo stretchy=\"false\">)</mml:mo>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">M\\backslash N(K)</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is at least twice the rank of the sutured Floer homology of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper M\">\n <mml:semantics>\n <mml:mi>M</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">M</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. This paper studies the properties of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper K\">\n <mml:semantics>\n <mml:mi>K</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">K</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> when the equality is achieved for instanton homology. As an application, we show that if <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper L subset-of upper S cubed\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>L</mml:mi>\n <mml:mo>⊂<!-- ⊂ --></mml:mo>\n <mml:msup>\n <mml:mi>S</mml:mi>\n <mml:mn>3</mml:mn>\n </mml:msup>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">L\\subset S^3</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is a fixed link and <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper K\">\n <mml:semantics>\n <mml:mi>K</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">K</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is a knot in the complement of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper L\">\n <mml:semantics>\n <mml:mi>L</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">L</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>, then the instanton link Floer homology of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper L union upper K\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>L</mml:mi>\n <mml:mo>∪<!-- ∪ --></mml:mo>\n <mml:mi>K</mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">L\\cup K</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> achieves the minimum rank if and only if <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper K\">\n <mml:semantics>\n <mml:mi>K</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">K</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> is the unknot in <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper S cubed minus upper L\">\n <mml:semantics>\n <mml:mrow>\n <mml:msup>\n <mml:mi>S</mml:mi>\n <mml:mn>3</mml:mn>\n </mml:msup>\n <mml:mi class=\"MJX-variant\" mathvariant=\"normal\">∖<!-- ∖ --></mml:mi>\n <mml:mi>L</mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">S^3\\backslash L</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>.</p>","PeriodicalId":377306,"journal":{"name":"Transactions of the American Mathematical Society, Series B","volume":"79 1","pages":"0"},"PeriodicalIF":0.0000,"publicationDate":"2021-08-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Transactions of the American Mathematical Society, Series B","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1090/btran/105","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 3
Abstract
Suppose (M,γ)(M, \gamma ) is a balanced sutured manifold and KK is a rationally null-homologous knot in MM. It is known that the rank of the sutured Floer homology of M∖N(K)M\backslash N(K) is at least twice the rank of the sutured Floer homology of MM. This paper studies the properties of KK when the equality is achieved for instanton homology. As an application, we show that if L⊂S3L\subset S^3 is a fixed link and KK is a knot in the complement of LL, then the instanton link Floer homology of L∪KL\cup K achieves the minimum rank if and only if KK is the unknot in S3∖LS^3\backslash L.