{"title":"模的有限性的一个判据","authors":"M. Khazaei, R. Sazeedeh","doi":"10.4171/rsmup/128","DOIUrl":null,"url":null,"abstract":"Let $A$ be a commutative noetherian ring, $\\frak a$ be an ideal of $A$, $m,n$ be non-negative integers and let $M$ be an $A$-module such that $\\Ext^i_A(A/\\frak a,M)$ is finitely generated for all $i\\leq m+n$. We define a class $\\cS_n(\\frak a)$ of modules and we assume that $H_{\\frak a}^s(M)\\in\\cS_{n}(\\frak a)$ for all $s\\leq m$. We show that $H_{\\frak a}^s(M)$ is $\\frak a$-cofinite for all $s\\leq m$ if either $n=1$ or $n\\geq 2$ and $\\Ext_A^{i}(A/\\frak a,H_{\\frak a}^{t+s-i}(M))$ is finitely generated for all $1\\leq t\\leq n-1$, $i\\leq t-1$ and $s\\leq m$. If $A$ is a ring of dimension $d$ and $M\\in\\cS_n(\\frak a)$ for any ideal $\\frak a$ of dimension $\\leq d-1$, then we prove that $M\\in\\cS_n(\\frak a)$ for any ideal $\\frak a$ of $A$.","PeriodicalId":20997,"journal":{"name":"Rendiconti del Seminario Matematico della Università di Padova","volume":"10 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2022-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"3","resultStr":"{\"title\":\"A criterion for cofiniteness of modules\",\"authors\":\"M. Khazaei, R. Sazeedeh\",\"doi\":\"10.4171/rsmup/128\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"Let $A$ be a commutative noetherian ring, $\\\\frak a$ be an ideal of $A$, $m,n$ be non-negative integers and let $M$ be an $A$-module such that $\\\\Ext^i_A(A/\\\\frak a,M)$ is finitely generated for all $i\\\\leq m+n$. We define a class $\\\\cS_n(\\\\frak a)$ of modules and we assume that $H_{\\\\frak a}^s(M)\\\\in\\\\cS_{n}(\\\\frak a)$ for all $s\\\\leq m$. We show that $H_{\\\\frak a}^s(M)$ is $\\\\frak a$-cofinite for all $s\\\\leq m$ if either $n=1$ or $n\\\\geq 2$ and $\\\\Ext_A^{i}(A/\\\\frak a,H_{\\\\frak a}^{t+s-i}(M))$ is finitely generated for all $1\\\\leq t\\\\leq n-1$, $i\\\\leq t-1$ and $s\\\\leq m$. If $A$ is a ring of dimension $d$ and $M\\\\in\\\\cS_n(\\\\frak a)$ for any ideal $\\\\frak a$ of dimension $\\\\leq d-1$, then we prove that $M\\\\in\\\\cS_n(\\\\frak a)$ for any ideal $\\\\frak a$ of $A$.\",\"PeriodicalId\":20997,\"journal\":{\"name\":\"Rendiconti del Seminario Matematico della Università di Padova\",\"volume\":\"10 1\",\"pages\":\"\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"2022-01-12\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"3\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Rendiconti del Seminario Matematico della Università di Padova\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.4171/rsmup/128\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Rendiconti del Seminario Matematico della Università di Padova","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.4171/rsmup/128","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Let $A$ be a commutative noetherian ring, $\frak a$ be an ideal of $A$, $m,n$ be non-negative integers and let $M$ be an $A$-module such that $\Ext^i_A(A/\frak a,M)$ is finitely generated for all $i\leq m+n$. We define a class $\cS_n(\frak a)$ of modules and we assume that $H_{\frak a}^s(M)\in\cS_{n}(\frak a)$ for all $s\leq m$. We show that $H_{\frak a}^s(M)$ is $\frak a$-cofinite for all $s\leq m$ if either $n=1$ or $n\geq 2$ and $\Ext_A^{i}(A/\frak a,H_{\frak a}^{t+s-i}(M))$ is finitely generated for all $1\leq t\leq n-1$, $i\leq t-1$ and $s\leq m$. If $A$ is a ring of dimension $d$ and $M\in\cS_n(\frak a)$ for any ideal $\frak a$ of dimension $\leq d-1$, then we prove that $M\in\cS_n(\frak a)$ for any ideal $\frak a$ of $A$.