{"title":"The density of Meissner polyhedra","authors":"Ryan Hynd","doi":"10.1007/s10711-024-00933-z","DOIUrl":"https://doi.org/10.1007/s10711-024-00933-z","url":null,"abstract":"<p>We consider Meissner polyhedra in <span>(mathbb {R}^3)</span>. These are constant width bodies whose boundaries consist of pieces of spheres and spindle tori. We define these shapes by taking appropriate intersections of congruent balls and show that they are dense within the space of constant width bodies in the Hausdorff topology. This density assertion was essentially established by Sallee. However, we offer a modern viewpoint taking into consideration the recent progress in understanding ball polyhedra and in constructing constant width bodies based on these shapes.\u0000</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141742572","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Lower bound for KVol on the minimal stratum of translation surfaces","authors":"Julien Boulanger","doi":"10.1007/s10711-024-00937-9","DOIUrl":"https://doi.org/10.1007/s10711-024-00937-9","url":null,"abstract":"<p>In this paper we are interested in algebraic intersection of closed curves of a given length on translation surfaces. We study the quantity KVol, defined in Cheboui et al. (Bull Soc Math France 149(4):613–640, 2021) and studied in Cheboui et al. (2021), Cheboui et al. (C R Math Acad Sci Paris 359:65–70, 2021), Boulanger et al. (Ann Henri Lebesgue, 2024), and Boulanger (Algebraic intersection, lengths and Veech surfaces, 2023. arXiv:2309.17165), and we construct families of translation surfaces in each connected component of the minimal stratum <span>(mathcal {H}(2g-2))</span> of the moduli space of translation surfaces of genus <span>(g ge 2)</span> such that KVol is arbitrarily close to the genus of the surface, which is conjectured to be the infimum of KVol on <span>(mathcal {H}(2g-2))</span>.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141584574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A criterion for Lie algebroid connections on a compact Riemann surface","authors":"Indranil Biswas, Pradip Kumar, Anoop Singh","doi":"10.1007/s10711-024-00938-8","DOIUrl":"https://doi.org/10.1007/s10711-024-00938-8","url":null,"abstract":"<p>Let <i>X</i> be a compact connected Riemann surface and <span>((V,, phi ))</span> a holomorphic Lie algebroid on <i>X</i> such that the holomorphic vector bundle <i>V</i> is stable. We give a necessary and sufficient condition on holomorphic vector bundles <i>E</i> on <i>X</i> to admit a Lie algebroid connection.\u0000</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141509540","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Trisecting a 4-dimensional book into three chapters","authors":"Marc Kegel, Felix Schmäschke","doi":"10.1007/s10711-024-00932-0","DOIUrl":"https://doi.org/10.1007/s10711-024-00932-0","url":null,"abstract":"<p>We describe an algorithm that takes as input an open book decomposition of a closed oriented 4-manifold and outputs an explicit trisection diagram of that 4-manifold. Moreover, a slight variation of this algorithm also works for open books on manifolds with non-empty boundary and for 3-manifold bundles over <span>(S^1)</span>. We apply this algorithm to several simple open books, demonstrate that it is compatible with various topological constructions, and argue that it generalizes and unifies several previously known constructions.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141509541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Projectively induced Kähler cones over regular Sasakian manifolds","authors":"Stefano Marini, Nicoletta Tardini, Michela Zedda","doi":"10.1007/s10711-024-00935-x","DOIUrl":"https://doi.org/10.1007/s10711-024-00935-x","url":null,"abstract":"<p>Motivated by a conjecture in Loi et al. (Math Zeit 290:599–613, 2018) we prove that the Kähler cone over a regular complete Sasakian manifold is Ricci-flat and projectively induced if and only if it is flat. We also obtain that, up to <span>(mathcal D_a)</span>—homothetic transformations, Kähler cones over homogeneous compact Sasakian manifolds are projectively induced. As main tool we provide a relation between the Kähler potentials of the transverse Kähler metric and of the cone metric.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141530071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"The Menger curve and spherical CR uniformization of a closed hyperbolic 3-orbifold","authors":"Jiming Ma, Baohua Xie","doi":"10.1007/s10711-024-00934-y","DOIUrl":"https://doi.org/10.1007/s10711-024-00934-y","url":null,"abstract":"<p>Let <span>(G_{6,3})</span> be a hyperbolic polygon-group with boundary the Menger curve. Granier (Groupes discrets en géométrie hyperbolique—aspects effectifs, Université de Fribourg, 2015) constructed a discrete, convex cocompact and faithful representation <span>(rho )</span> of <span>(G_{6,3})</span> into <span>(textbf{PU}(2,1))</span>. We show the 3-orbifold at infinity of <span>(rho (G_{6,3}))</span> is a closed hyperbolic 3-orbifold, with underlying space the 3-sphere and singular locus the <span>({mathbb {Z}}_3)</span>-coned chain-link <span>(C(6,-2))</span>. This answers the second part of Kapovich’s Conjecture 10.6 in Kapovich (in: In the tradition of thurston II. Geometry and groups, Springer, Cham, 2022), and it also provides the second explicit example of a closed hyperbolic 3-orbifold that admits a uniformizable spherical CR-structure after Schwartz’s first example in Schwartz (Invent Math 151(2):221–295, 2003).</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-06-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141509589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Chern–Simons theory and cohomological invariants of representation varieties","authors":"Nicolas Tholozan","doi":"10.1007/s10711-024-00926-y","DOIUrl":"https://doi.org/10.1007/s10711-024-00926-y","url":null,"abstract":"","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141123418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Isoperiodic families of Poncelet polygons inscribed in a circle and circumscribed about conics from a confocal pencil","authors":"Vladimir Dragović, Milena Radnović","doi":"10.1007/s10711-024-00929-9","DOIUrl":"https://doi.org/10.1007/s10711-024-00929-9","url":null,"abstract":"<p>Poncelet polygons inscribed in a circle and circumscribed about conics from a confocal family naturally arise in the analysis of the numerical range and Blaschke products. We examine the behaviour of such polygons when the inscribed conic varies through a confocal pencil and discover cases when each conic from the confocal family is inscribed in an <i>n</i>-polygon, which is inscribed in the circle, with the same <i>n</i>. Complete geometric characterization of such cases for <span>(nin {4,6})</span> is given and proved that this cannot happen for other values of <i>n</i>. We establish a relationship of such families of Poncelet quadrangles and hexagons to solutions of a Painlevé VI equation.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141060280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fundamental groups and group presentations with bounded relator lengths","authors":"Sergio Zamora","doi":"10.1007/s10711-024-00915-1","DOIUrl":"https://doi.org/10.1007/s10711-024-00915-1","url":null,"abstract":"<p>We study the geometry of compact geodesic spaces with trivial first Betti number admitting large finite groups of isometries. We show that if a finite group <i>G</i> acts by isometries on a compact geodesic space <i>X</i> whose first Betti number vanishes, then <span>({text {diam}}(X) / {text {diam}}(X / G ) le 4 sqrt{ vert G vert })</span>. For a group <i>G</i> and a finite symmetric generating set <i>S</i>, <span>(P_k(varGamma (G, S)))</span> denotes the 2-dimensional CW-complex whose 1-skeleton is the Cayley graph <span>(varGamma )</span> of <i>G</i> with respect to <i>S</i> and whose 2-cells are <i>m</i>-gons for <span>(0 le m le k)</span>, defined by the simple graph loops of length <i>m</i> in <span>(varGamma )</span>, up to cyclic permutations. Let <i>G</i> be a finite abelian group with <span>(vert G vert ge 3)</span> and <i>S</i> a symmetric set of generators for which <span>(P_k(varGamma (G,S)))</span> has trivial first Betti number. We show that the first nontrivial eigenvalue <span>(-lambda _1)</span> of the Laplacian on the Cayley graph satisfies <span>(lambda _1 ge 2 - 2 cos ( 2 pi / k ) )</span>. We also give an explicit upper bound on the diameter of the Cayley graph of <i>G</i> with respect to <i>S</i> of the form <span>(O (k^2 vert S vert log vert G vert ))</span>. Related explicit bounds for the Cheeger constant and Kazhdan constant of the pair (<i>G</i>, <i>S</i>) are also obtained.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":null,"pages":null},"PeriodicalIF":0.5,"publicationDate":"2024-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140929899","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}