{"title":"The birational geometry of $$\\overline{{\\mathcal {R}}}_{g,2}$$ and Prym-canonical divisorial strata","authors":"","doi":"10.1007/s00029-023-00907-1","DOIUrl":null,"url":null,"abstract":"<h3>Abstract</h3> <p>We prove that the moduli space of double covers ramified at two points <span> <span>\\({\\mathcal {R}}_{g,2}\\)</span> </span> is uniruled for <span> <span>\\(3\\le g\\le 6\\)</span> </span> and of general type for <span> <span>\\(g\\ge 16\\)</span> </span>. Furthermore, we consider Prym-canonical divisorial strata in the moduli space <span> <span>\\(\\overline{{\\mathcal {C}}^n{\\mathcal {R}}}_g\\)</span> </span> parametrizing <em>n</em>-pointed Prym curves, and we compute their classes in <span> <span>\\(\\textrm{Pic}_{\\mathbb {Q}}(\\overline{{\\mathcal {C}}^n{\\mathcal {R}}}_g)\\)</span> </span>. </p>","PeriodicalId":501600,"journal":{"name":"Selecta Mathematica","volume":"43 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Selecta Mathematica","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1007/s00029-023-00907-1","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
We prove that the moduli space of double covers ramified at two points \({\mathcal {R}}_{g,2}\) is uniruled for \(3\le g\le 6\) and of general type for \(g\ge 16\). Furthermore, we consider Prym-canonical divisorial strata in the moduli space \(\overline{{\mathcal {C}}^n{\mathcal {R}}}_g\) parametrizing n-pointed Prym curves, and we compute their classes in \(\textrm{Pic}_{\mathbb {Q}}(\overline{{\mathcal {C}}^n{\mathcal {R}}}_g)\).