{"title":"图的同源线性商和边沿理想","authors":"NADIA TAGHIPOUR, SHAMILA BAYATI, FARHAD RAHMATI","doi":"10.1017/s0004972723001363","DOIUrl":null,"url":null,"abstract":"It is well known that the edge ideal <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline1.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> of a simple graph <jats:italic>G</jats:italic> has linear quotients if and only if <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline2.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is chordal. We investigate when the property of having linear quotients is inherited by homological shift ideals of an edge ideal. We will see that adding a cluster to the graph <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline3.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> when <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline4.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients results in a graph with the same property. In particular, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline5.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients when <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline6.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a block graph. We also show that adding pinnacles to trees preserves the property of having homological linear quotients for the edge ideal of their complements. Furthermore, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline7.png\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients for every graph <jats:italic>G</jats:italic> such that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline8.png\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\"http://www.w3.org/1999/xlink\" mime-subtype=\"png\" xlink:href=\"S0004972723001363_inline9.png\" /> <jats:tex-math> $\\lambda $ </jats:tex-math> </jats:alternatives> </jats:inline-formula>-minimal chordal graph.","PeriodicalId":50720,"journal":{"name":"Bulletin of the Australian Mathematical Society","volume":"38 1","pages":""},"PeriodicalIF":0.6000,"publicationDate":"2024-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"HOMOLOGICAL LINEAR QUOTIENTS AND EDGE IDEALS OF GRAPHS\",\"authors\":\"NADIA TAGHIPOUR, SHAMILA BAYATI, FARHAD RAHMATI\",\"doi\":\"10.1017/s0004972723001363\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"It is well known that the edge ideal <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline1.png\\\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> of a simple graph <jats:italic>G</jats:italic> has linear quotients if and only if <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline2.png\\\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is chordal. We investigate when the property of having linear quotients is inherited by homological shift ideals of an edge ideal. We will see that adding a cluster to the graph <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline3.png\\\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> when <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline4.png\\\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients results in a graph with the same property. In particular, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline5.png\\\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients when <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline6.png\\\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a block graph. We also show that adding pinnacles to trees preserves the property of having homological linear quotients for the edge ideal of their complements. Furthermore, <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline7.png\\\" /> <jats:tex-math> $I(G)$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> has homological linear quotients for every graph <jats:italic>G</jats:italic> such that <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline8.png\\\" /> <jats:tex-math> $G^c$ </jats:tex-math> </jats:alternatives> </jats:inline-formula> is a <jats:inline-formula> <jats:alternatives> <jats:inline-graphic xmlns:xlink=\\\"http://www.w3.org/1999/xlink\\\" mime-subtype=\\\"png\\\" xlink:href=\\\"S0004972723001363_inline9.png\\\" /> <jats:tex-math> $\\\\lambda $ </jats:tex-math> </jats:alternatives> </jats:inline-formula>-minimal chordal graph.\",\"PeriodicalId\":50720,\"journal\":{\"name\":\"Bulletin of the Australian Mathematical Society\",\"volume\":\"38 1\",\"pages\":\"\"},\"PeriodicalIF\":0.6000,\"publicationDate\":\"2024-01-29\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Bulletin of the Australian Mathematical Society\",\"FirstCategoryId\":\"100\",\"ListUrlMain\":\"https://doi.org/10.1017/s0004972723001363\",\"RegionNum\":4,\"RegionCategory\":\"数学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"MATHEMATICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Bulletin of the Australian Mathematical Society","FirstCategoryId":"100","ListUrlMain":"https://doi.org/10.1017/s0004972723001363","RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"MATHEMATICS","Score":null,"Total":0}
HOMOLOGICAL LINEAR QUOTIENTS AND EDGE IDEALS OF GRAPHS
It is well known that the edge ideal $I(G)$ of a simple graph G has linear quotients if and only if $G^c$ is chordal. We investigate when the property of having linear quotients is inherited by homological shift ideals of an edge ideal. We will see that adding a cluster to the graph $G^c$ when $I(G)$ has homological linear quotients results in a graph with the same property. In particular, $I(G)$ has homological linear quotients when $G^c$ is a block graph. We also show that adding pinnacles to trees preserves the property of having homological linear quotients for the edge ideal of their complements. Furthermore, $I(G)$ has homological linear quotients for every graph G such that $G^c$ is a $\lambda $ -minimal chordal graph.
期刊介绍:
Bulletin of the Australian Mathematical Society aims at quick publication of original research in all branches of mathematics. Papers are accepted only after peer review but editorial decisions on acceptance or otherwise are taken quickly, normally within a month of receipt of the paper. The Bulletin concentrates on presenting new and interesting results in a clear and attractive way.
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Published for the Australian Mathematical Society