{"title":"Moduli of finite flat torsors over nodal curves","authors":"Sara Mehidi, Thibault Poiret","doi":"10.1112/jlms.70220","DOIUrl":null,"url":null,"abstract":"<p>We show that log flat torsors over a family <span></span><math>\n <semantics>\n <mrow>\n <mi>X</mi>\n <mo>/</mo>\n <mi>S</mi>\n </mrow>\n <annotation>$X/S$</annotation>\n </semantics></math> of nodal curves under a finite flat commutative group scheme <span></span><math>\n <semantics>\n <mrow>\n <mi>G</mi>\n <mo>/</mo>\n <mi>S</mi>\n </mrow>\n <annotation>$G/S$</annotation>\n </semantics></math> are classified by maps from the Cartier dual of <span></span><math>\n <semantics>\n <mi>G</mi>\n <annotation>$G$</annotation>\n </semantics></math> to the log Jacobian of <span></span><math>\n <semantics>\n <mi>X</mi>\n <annotation>$X$</annotation>\n </semantics></math>. We deduce that fppf torsors on the smooth fiberss of <span></span><math>\n <semantics>\n <mrow>\n <mi>X</mi>\n <mo>/</mo>\n <mi>S</mi>\n </mrow>\n <annotation>$X/S$</annotation>\n </semantics></math> can be extended to global log flat torsors under some regularity hypotheses.</p>","PeriodicalId":49989,"journal":{"name":"Journal of the London Mathematical Society-Second Series","volume":"112 1","pages":""},"PeriodicalIF":1.0000,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/jlms.70220","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the London Mathematical Society-Second Series","FirstCategoryId":"100","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1112/jlms.70220","RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATHEMATICS","Score":null,"Total":0}
We show that log flat torsors over a family of nodal curves under a finite flat commutative group scheme are classified by maps from the Cartier dual of to the log Jacobian of . We deduce that fppf torsors on the smooth fiberss of can be extended to global log flat torsors under some regularity hypotheses.
期刊介绍:
The Journal of the London Mathematical Society has been publishing leading research in a broad range of mathematical subject areas since 1926. The Journal welcomes papers on subjects of general interest that represent a significant advance in mathematical knowledge, as well as submissions that are deemed to stimulate new interest and research activity.