{"title":"Multiplicative Invariant Fields of Dimension ≤6","authors":"A. Hoshi, M. Kang, A. Yamasaki","doi":"10.1090/memo/1403","DOIUrl":null,"url":null,"abstract":"<p>The finite subgroups of <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper G upper L 4 left-parenthesis double-struck upper Z right-parenthesis\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>G</mml:mi>\n <mml:msub>\n <mml:mi>L</mml:mi>\n <mml:mn>4</mml:mn>\n </mml:msub>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">Z</mml:mi>\n </mml:mrow>\n <mml:mo stretchy=\"false\">)</mml:mo>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">GL_4(\\mathbb {Z})</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> are classified up to conjugation in Brown, Büllow, Neubüser, Wondratscheck, and Zassenhaus (1978); in particular, there exist <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"710\">\n <mml:semantics>\n <mml:mn>710</mml:mn>\n <mml:annotation encoding=\"application/x-tex\">710</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> non-conjugate finite groups in <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper G upper L 4 left-parenthesis double-struck upper Z right-parenthesis\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>G</mml:mi>\n <mml:msub>\n <mml:mi>L</mml:mi>\n <mml:mn>4</mml:mn>\n </mml:msub>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">Z</mml:mi>\n </mml:mrow>\n <mml:mo stretchy=\"false\">)</mml:mo>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">GL_4(\\mathbb {Z})</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. Each finite group <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper G\">\n <mml:semantics>\n <mml:mi>G</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">G</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 G upper L 4 left-parenthesis double-struck upper Z right-parenthesis\">\n <mml:semantics>\n <mml:mrow>\n <mml:mi>G</mml:mi>\n <mml:msub>\n <mml:mi>L</mml:mi>\n <mml:mn>4</mml:mn>\n </mml:msub>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">Z</mml:mi>\n </mml:mrow>\n <mml:mo stretchy=\"false\">)</mml:mo>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">GL_4(\\mathbb {Z})</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> acts naturally on <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"double-struck upper Z Superscript circled-plus 4\">\n <mml:semantics>\n <mml:msup>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">Z</mml:mi>\n </mml:mrow>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mo>⊕<!-- ⊕ --></mml:mo>\n <mml:mn>4</mml:mn>\n </mml:mrow>\n </mml:msup>\n <mml:annotation encoding=\"application/x-tex\">\\mathbb {Z}^{\\oplus 4}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>; thus we get a faithful <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper G\">\n <mml:semantics>\n <mml:mi>G</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">G</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>-lattice <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> with <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"normal r normal a normal n normal k Subscript double-struck upper Z Baseline upper M equals 4\">\n <mml:semantics>\n <mml:mrow>\n <mml:msub>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"normal\">r</mml:mi>\n <mml:mi mathvariant=\"normal\">a</mml:mi>\n <mml:mi mathvariant=\"normal\">n</mml:mi>\n <mml:mi mathvariant=\"normal\">k</mml:mi>\n </mml:mrow>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">Z</mml:mi>\n </mml:mrow>\n </mml:msub>\n <mml:mi>M</mml:mi>\n <mml:mo>=</mml:mo>\n <mml:mn>4</mml:mn>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathrm {rank}_\\mathbb {Z} M=4</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. In this way, there are exactly <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"710\">\n <mml:semantics>\n <mml:mn>710</mml:mn>\n <mml:annotation encoding=\"application/x-tex\">710</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> such lattices. Given a <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper G\">\n <mml:semantics>\n <mml:mi>G</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">G</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>-lattice <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> with <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"normal r normal a normal n normal k Subscript double-struck upper Z Baseline upper M equals 4\">\n <mml:semantics>\n <mml:mrow>\n <mml:msub>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"normal\">r</mml:mi>\n <mml:mi mathvariant=\"normal\">a</mml:mi>\n <mml:mi mathvariant=\"normal\">n</mml:mi>\n <mml:mi mathvariant=\"normal\">k</mml:mi>\n </mml:mrow>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">Z</mml:mi>\n </mml:mrow>\n </mml:msub>\n <mml:mi>M</mml:mi>\n <mml:mo>=</mml:mo>\n <mml:mn>4</mml:mn>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathrm {rank}_\\mathbb {Z} M=4</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>, the group <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"upper G\">\n <mml:semantics>\n <mml:mi>G</mml:mi>\n <mml:annotation encoding=\"application/x-tex\">G</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> acts on the rational function field <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"double-struck upper C left-parenthesis upper M right-parenthesis colon-equal double-struck upper C left-parenthesis x 1 comma x 2 comma x 3 comma x 4 right-parenthesis\">\n <mml:semantics>\n <mml:mrow>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">C</mml:mi>\n </mml:mrow>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mi>M</mml:mi>\n <mml:mo stretchy=\"false\">)</mml:mo>\n <mml:mo>≔</mml:mo>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">C</mml:mi>\n </mml:mrow>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:msub>\n <mml:mi>x</mml:mi>\n <mml:mn>1</mml:mn>\n </mml:msub>\n <mml:mo>,</mml:mo>\n <mml:msub>\n <mml:mi>x</mml:mi>\n <mml:mn>2</mml:mn>\n </mml:msub>\n <mml:mo>,</mml:mo>\n <mml:msub>\n <mml:mi>x</mml:mi>\n <mml:mn>3</mml:mn>\n </mml:msub>\n <mml:mo>,</mml:mo>\n <mml:msub>\n <mml:mi>x</mml:mi>\n <mml:mn>4</mml:mn>\n </mml:msub>\n <mml:mo stretchy=\"false\">)</mml:mo>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathbb {C}(M)≔\\mathbb {C}(x_1,x_2,x_3,x_4)</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula> by multiplicative actions, i.e. purely monomial automorphisms over <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"double-struck upper C\">\n <mml:semantics>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">C</mml:mi>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathbb {C}</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. We are concerned with the rationality problem of the fixed field <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"double-struck upper C left-parenthesis upper M right-parenthesis Superscript upper G\">\n <mml:semantics>\n <mml:mrow>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">C</mml:mi>\n </mml:mrow>\n <mml:mo stretchy=\"false\">(</mml:mo>\n <mml:mi>M</mml:mi>\n <mml:msup>\n <mml:mo stretchy=\"false\">)</mml:mo>\n <mml:mi>G</mml:mi>\n </mml:msup>\n </mml:mrow>\n <mml:annotation encoding=\"application/x-tex\">\\mathbb {C}(M)^G</mml:annotation>\n </mml:semantics>\n</mml:math>\n</inline-formula>. A tool of our investigation is the unramified Brauer group of the field <inline-formula content-type=\"math/mathml\">\n<mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" alttext=\"double-struck upper C left-parenthesis upper M right-parenthesis Superscript upper G\">\n <mml:semantics>\n <mml:mrow>\n <mml:mrow class=\"MJX-TeXAtom-ORD\">\n <mml:mi mathvariant=\"double-struck\">C</mml:mi>\n </mml:mrow>\n <mml:mo str","PeriodicalId":2,"journal":{"name":"ACS Applied Bio Materials","volume":null,"pages":null},"PeriodicalIF":4.6000,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Applied Bio Materials","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1090/memo/1403","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, BIOMATERIALS","Score":null,"Total":0}
引用次数: 0
Abstract
The finite subgroups of GL4(Z)GL_4(\mathbb {Z}) are classified up to conjugation in Brown, Büllow, Neubüser, Wondratscheck, and Zassenhaus (1978); in particular, there exist 710710 non-conjugate finite groups in GL4(Z)GL_4(\mathbb {Z}). Each finite group GG of GL4(Z)GL_4(\mathbb {Z}) acts naturally on Z⊕4\mathbb {Z}^{\oplus 4}; thus we get a faithful GG-lattice MM with rankZM=4\mathrm {rank}_\mathbb {Z} M=4. In this way, there are exactly 710710 such lattices. Given a GG-lattice MM with rankZM=4\mathrm {rank}_\mathbb {Z} M=4, the group GG acts on the rational function field C(M)≔C(x1,x2,x3,x4)\mathbb {C}(M)≔\mathbb {C}(x_1,x_2,x_3,x_4) by multiplicative actions, i.e. purely monomial automorphisms over C\mathbb {C}. We are concerned with the rationality problem of the fixed field C(M)G\mathbb {C}(M)^G. A tool of our investigation is the unramified Brauer group of the field C
在Brown,Büllow,Neubüser,Wondratscheck和Zassenhaus(1978)中,对G L 4(Z)GL_4(\mathbb{Z})的有限子群进行了共轭分类;特别地,在G L4(Z)GL_4(\mathbb{Z})中存在710 710个非共轭有限群。G L4(Z)GL_4(\mathbb{Z})的每个有限群G G自然作用于ZŞ4\mathbb{Z}^{\oplus 4};因此我们得到了一个忠实的G G-格M M,其中r a n k Z M=4{rank}_\mathb{Z}M=4。通过这种方式,正好有710 710个这样的晶格。给定一个具有r a n k Z M=4\ mathrm的G G-格M M{rank}_\mathbb{Z}M=4,群G G通过乘法作用作用于有理函数域C(M)≔C(x1,x2,x3,x4)\mathbb{C}(M)\ mathbb{C}(x_1,x_2,x_3,x_4),即C\mathbb{C}上的纯单体自同构。我们讨论了固定域C(M)G\mathbb{C}(M)^G的合理性问题。我们研究的一个工具是域C