Spencer Dowdall, Matthew G. Durham, Christopher J. Leininger, Alessandro Sisto
{"title":"Extensions of Veech groups I: A hyperbolic action","authors":"Spencer Dowdall, Matthew G. Durham, Christopher J. Leininger, Alessandro Sisto","doi":"10.1112/topo.12296","DOIUrl":"10.1112/topo.12296","url":null,"abstract":"<p>Given a lattice Veech group in the mapping class group of a closed surface <math>\u0000 <semantics>\u0000 <mi>S</mi>\u0000 <annotation>$S$</annotation>\u0000 </semantics></math>, this paper investigates the geometry of <math>\u0000 <semantics>\u0000 <mi>Γ</mi>\u0000 <annotation>$Gamma$</annotation>\u0000 </semantics></math>, the associated <math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>π</mi>\u0000 <mn>1</mn>\u0000 </msub>\u0000 <mi>S</mi>\u0000 </mrow>\u0000 <annotation>$pi _1S$</annotation>\u0000 </semantics></math>-extension group. We prove that <math>\u0000 <semantics>\u0000 <mi>Γ</mi>\u0000 <annotation>$Gamma$</annotation>\u0000 </semantics></math> is the fundamental group of a bundle with a singular Euclidean-by-hyperbolic geometry. Our main result is that collapsing “obvious” product regions of the universal cover produces an action of <math>\u0000 <semantics>\u0000 <mi>Γ</mi>\u0000 <annotation>$Gamma$</annotation>\u0000 </semantics></math> on a hyperbolic space, retaining most of the geometry of <math>\u0000 <semantics>\u0000 <mi>Γ</mi>\u0000 <annotation>$Gamma$</annotation>\u0000 </semantics></math>. This action is a key ingredient in the sequel where we show that <math>\u0000 <semantics>\u0000 <mi>Γ</mi>\u0000 <annotation>$Gamma$</annotation>\u0000 </semantics></math> is hierarchically hyperbolic and quasi-isometrically rigid.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/topo.12296","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47266131","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Split link detection for \u0000 \u0000 \u0000 sl\u0000 (\u0000 P\u0000 )\u0000 \u0000 $mathfrak {sl}(P)$\u0000 link homology in characteristic \u0000 \u0000 P\u0000 $P$","authors":"Joshua Wang","doi":"10.1112/topo.12297","DOIUrl":"10.1112/topo.12297","url":null,"abstract":"<p>We provide a sufficient condition for splitness of a link in terms of its reduced <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>sl</mi>\u0000 <mo>(</mo>\u0000 <mi>N</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$mathfrak {sl}(N)$</annotation>\u0000 </semantics></math> link homology with arbitrary field coefficients. The proof of sufficiency uses Dowlin's spectral sequence and sutured Floer homology with twisted coefficients. If <math>\u0000 <semantics>\u0000 <mi>N</mi>\u0000 <annotation>$N$</annotation>\u0000 </semantics></math> is prime and the coefficient field is of characteristic <math>\u0000 <semantics>\u0000 <mi>N</mi>\u0000 <annotation>$N$</annotation>\u0000 </semantics></math>, then the sufficient condition for splitness is also necessary. When <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>N</mi>\u0000 <mo>=</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation>$N = 2$</annotation>\u0000 </semantics></math>, we recover Lipshitz–Sarkar's split link detection result for Khovanov homology with <math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>Z</mi>\u0000 <mo>/</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation>$mathbf {Z}/2$</annotation>\u0000 </semantics></math> coefficients.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43711926","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}