{"title":"Derived deformation theory of crepant curves","authors":"Gavin Brown, Michael Wemyss","doi":"10.1112/topo.12359","DOIUrl":"https://doi.org/10.1112/topo.12359","url":null,"abstract":"<p>This paper determines the full, derived deformation theory of certain smooth rational curves <span></span><math>\u0000 <semantics>\u0000 <mi>C</mi>\u0000 <annotation>$mathrm{C}$</annotation>\u0000 </semantics></math> in Calabi–Yau 3-folds, by determining all higher <span></span><math>\u0000 <semantics>\u0000 <msub>\u0000 <mi>A</mi>\u0000 <mi>∞</mi>\u0000 </msub>\u0000 <annotation>$mathrm{A}_infty$</annotation>\u0000 </semantics></math>-products in its controlling DG-algebra. This geometric setup includes very general cases where <span></span><math>\u0000 <semantics>\u0000 <mi>C</mi>\u0000 <annotation>$mathrm{C}$</annotation>\u0000 </semantics></math> does not contract, cases where the curve neighbourhood is not rational, all known simple smooth 3-fold flops, and all known divisorial contractions to curves. As a corollary, it is shown that the non-commutative deformation theory of <span></span><math>\u0000 <semantics>\u0000 <mi>C</mi>\u0000 <annotation>$mathrm{C}$</annotation>\u0000 </semantics></math> is described via a superpotential algebra derived from what we call free necklace polynomials, which are elements in the free algebra obtained via a closed formula from combinatorial gluing data. The description of these polynomials, together with the above results, establishes a suitably interpreted string theory prediction due to Ferrari (<i>Adv. Theor. Math. Phys</i>. <b>7</b> (2003) 619–665), Aspinwall–Katz (<i>Comm. Math. Phys</i>.. <b>264</b> (2006) 227–253) and Curto–Morrison (<i>J. Algebraic Geom</i>. <b>22</b> (2013) 599–627). Perhaps most significantly, the main results give both the language and evidence to finally formulate new contractibility conjectures for rational curves in CY 3-folds, which lift Artin's (<i>Amer. J. Math</i>. <b>84</b> (1962) 485–496) celebrated results from surfaces.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/topo.12359","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438990","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":"Calabi–Yau structures on Rabinowitz Fukaya categories","authors":"Hanwool Bae, Wonbo Jeong, Jongmyeong Kim","doi":"10.1112/topo.12361","DOIUrl":"https://doi.org/10.1112/topo.12361","url":null,"abstract":"<p>In this paper, we prove that the derived Rabinowitz Fukaya category of a Liouville domain <span></span><math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$M$</annotation>\u0000 </semantics></math> of dimension <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>2</mn>\u0000 <mi>n</mi>\u0000 </mrow>\u0000 <annotation>$2n$</annotation>\u0000 </semantics></math> is <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>n</mi>\u0000 <mo>−</mo>\u0000 <mn>1</mn>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$(n-1)$</annotation>\u0000 </semantics></math>-Calabi–Yau, assuming that the wrapped Fukaya category of <span></span><math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$M$</annotation>\u0000 </semantics></math> admits an at most countable set of Lagrangians that generate it and satisfy some finiteness condition on morphism spaces between them.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434974","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}
{"title":"Oriented Birkhoff sections of Anosov flows","authors":"Masayuki Asaoka, Christian Bonatti, Théo Marty","doi":"10.1112/topo.12356","DOIUrl":"https://doi.org/10.1112/topo.12356","url":null,"abstract":"<p>This paper gives three different proofs (independently obtained by the three authors) of the following fact: given an Anosov flow on an oriented 3-manifold, the existence of a positive Birkhoff section is equivalent to the fact that the flow is <span></span><math>\u0000 <semantics>\u0000 <mi>R</mi>\u0000 <annotation>$mathbb {R}$</annotation>\u0000 </semantics></math>-covered positively twisted.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434973","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}
{"title":"On the homology of big mapping class groups","authors":"Martin Palmer, Xiaolei Wu","doi":"10.1112/topo.12358","DOIUrl":"https://doi.org/10.1112/topo.12358","url":null,"abstract":"<p>We prove that the mapping class group of the one-holed Cantor tree surface is acyclic. This in turn determines the homology of the mapping class group of the once-punctured Cantor tree surface (i.e. the plane minus a Cantor set), in particular answering a recent question of Calegari and Chen. We in fact prove these results for a general class of infinite-type surfaces called binary tree surfaces. To prove our results we use two main ingredients: one is a modification of an argument of Mather related to the notion of <i>dissipated groups</i>; the other is a general homological stability result for mapping class groups of infinite-type surfaces.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/topo.12358","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142435193","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":"A realisation result for moduli spaces of group actions on the line","authors":"Joaquín Brum, Nicolás Matte Bon, Cristóbal Rivas, Michele Triestino","doi":"10.1112/topo.12357","DOIUrl":"https://doi.org/10.1112/topo.12357","url":null,"abstract":"<p>Given a finitely generated group <span></span><math>\u0000 <semantics>\u0000 <mi>G</mi>\u0000 <annotation>$G$</annotation>\u0000 </semantics></math>, the possible actions of <span></span><math>\u0000 <semantics>\u0000 <mi>G</mi>\u0000 <annotation>$G$</annotation>\u0000 </semantics></math> on the real line (without global fixed points), considered up to semi-conjugacy, can be encoded by the space of orbits of a flow on a compact space <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>Y</mi>\u0000 <mo>,</mo>\u0000 <mi>Φ</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$(Y, Phi)$</annotation>\u0000 </semantics></math> naturally associated with <span></span><math>\u0000 <semantics>\u0000 <mi>G</mi>\u0000 <annotation>$G$</annotation>\u0000 </semantics></math> and uniquely defined up to flow equivalence, that we call the <i>Deroin space</i> of <span></span><math>\u0000 <semantics>\u0000 <mi>G</mi>\u0000 <annotation>$G$</annotation>\u0000 </semantics></math>. We show a realisation result: every expansive flow <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>Y</mi>\u0000 <mo>,</mo>\u0000 <mi>Φ</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 <annotation>$(Y, Phi)$</annotation>\u0000 </semantics></math> on a compact metrisable space of topological dimension 1, satisfying some mild additional assumptions, arises as the Deroin space of a finitely generated group. This is proven by identifying the Deroin space of an explicit family of groups acting on suspension flows of subshifts, which is a variant of a construction introduced by the second and fourth authors. This result provides a source of examples of finitely generated groups satisfying various new phenomena for actions on the line, related to their rigidity/flexibility properties and to the structure of (path-)connected components of the space of actions.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142435192","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}
{"title":"Morse numbers of complex polynomials","authors":"Laurenţiu Maxim, Mihai Tibăr","doi":"10.1112/topo.12362","DOIUrl":"https://doi.org/10.1112/topo.12362","url":null,"abstract":"<p>To a complex polynomial function <span></span><math>\u0000 <semantics>\u0000 <mi>f</mi>\u0000 <annotation>$f$</annotation>\u0000 </semantics></math> with arbitrary singularities, we associate the number of Morse points in a general linear Morsification <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>f</mi>\u0000 <mi>t</mi>\u0000 </msub>\u0000 <mo>:</mo>\u0000 <mo>=</mo>\u0000 <mi>f</mi>\u0000 <mo>−</mo>\u0000 <mi>t</mi>\u0000 <mi>ℓ</mi>\u0000 </mrow>\u0000 <annotation>$f_{t}:= f - tell$</annotation>\u0000 </semantics></math>. We produce computable algebraic formulae in terms of invariants of <span></span><math>\u0000 <semantics>\u0000 <mi>f</mi>\u0000 <annotation>$f$</annotation>\u0000 </semantics></math> for the numbers of stratwise Morse trajectories that abut, as <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>t</mi>\u0000 <mo>→</mo>\u0000 <mn>0</mn>\u0000 </mrow>\u0000 <annotation>$trightarrow 0$</annotation>\u0000 </semantics></math>, to some point of the space or at infinity.</p>","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 4","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1112/topo.12362","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142435191","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":"Stated SL(\u0000 \u0000 n\u0000 $n$\u0000 )-skein modules and algebras","authors":"Thang T. Q. Lê, Adam S. Sikora","doi":"10.1112/topo.12350","DOIUrl":"https://doi.org/10.1112/topo.12350","url":null,"abstract":"<p>We develop a theory of stated SL(<span></span><math>\u0000 <semantics>\u0000 <mi>n</mi>\u0000 <annotation>$n$</annotation>\u0000 </semantics></math>)-skein modules, <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>S</mi>\u0000 <mi>n</mi>\u0000 </msub>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>M</mi>\u0000 <mo>,</mo>\u0000 <mi>N</mi>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$mathcal {S}_n(M,mathcal {N})$</annotation>\u0000 </semantics></math>, of 3-manifolds <span></span><math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$M$</annotation>\u0000 </semantics></math> marked with intervals <span></span><math>\u0000 <semantics>\u0000 <mi>N</mi>\u0000 <annotation>$mathcal {N}$</annotation>\u0000 </semantics></math> in their boundaries. These skein modules, generalizing stated SL(2)-modules of the first author, stated SL(3)-modules of Higgins', and SU(n)-skein modules of the second author, consist of linear combinations of framed, oriented graphs, called <span></span><math>\u0000 <semantics>\u0000 <mi>n</mi>\u0000 <annotation>$n$</annotation>\u0000 </semantics></math>-webs, with ends in <span></span><math>\u0000 <semantics>\u0000 <mi>N</mi>\u0000 <annotation>$mathcal {N}$</annotation>\u0000 </semantics></math>, considered up to skein relations of the <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>U</mi>\u0000 <mi>q</mi>\u0000 </msub>\u0000 <mrow>\u0000 <mo>(</mo>\u0000 <mi>s</mi>\u0000 <msub>\u0000 <mi>l</mi>\u0000 <mi>n</mi>\u0000 </msub>\u0000 <mo>)</mo>\u0000 </mrow>\u0000 </mrow>\u0000 <annotation>$U_q(sl_n)$</annotation>\u0000 </semantics></math>-Reshetikhin–Turaev functor on tangles, involving coupons representing the anti-symmetrizer and its dual. We prove the Splitting Theorem asserting that cutting of a marked 3-manifold <span></span><math>\u0000 <semantics>\u0000 <mi>M</mi>\u0000 <annotation>$M$</annotation>\u0000 </semantics></math> along a disk resulting in a 3-manifold <span></span><math>\u0000 <semantics>\u0000 <msup>\u0000 <mi>M</mi>\u0000 <mo>′</mo>\u0000 </msup>\u0000 <annotation>$M^{prime }$</annotation>\u0000 </semantics></math> yields a homomorphism <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <msub>\u0000 <mi>S</mi>\u0000 <mi>n</mi>\u0000 ","PeriodicalId":56114,"journal":{"name":"Journal of Topology","volume":"17 3","pages":""},"PeriodicalIF":0.8,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142041631","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}