{"title":"From $$L^p$$ bounds to Gromov–Hausdorff convergence of Riemannian manifolds","authors":"Brian Allen","doi":"10.1007/s10711-023-00875-y","DOIUrl":"https://doi.org/10.1007/s10711-023-00875-y","url":null,"abstract":"<p>In this paper we provide a way of taking <span>(L^p)</span>, <span>(p > frac{m}{2})</span> bounds on a <span>(m-)</span> dimensional Riemannian metric and transforming that into Hölder bounds for the corresponding distance function. One can think of this new estimate as a type of Morrey inequality for Riemannian manifolds where one thinks of a Riemannian metric as the gradient of the corresponding distance function so that the <span>(L^p)</span>, <span>(p > frac{m}{2})</span> bound analogously implies Hölder control on the distance function. This new estimate is then used to state a compactness theorem, another theorem which guarantees convergence to a particular Riemmanian manifold, and a new scalar torus stability result. We expect these results to be useful for proving geometric stability results in the presence of scalar curvature bounds when Gromov–Hausdorff convergence can be achieved.\u0000</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"22 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139082688","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}
Geometriae DedicataPub Date : 2024-01-01Epub Date: 2024-09-30DOI: 10.1007/s10711-024-00954-8
Thomas A Ivey, Spiro Karigiannis
{"title":"<ArticleTitle xmlns:ns0=\"http://www.w3.org/1998/Math/MathML\">Cohomogeneity one solitons for the isometric flow of <ns0:math><ns0:msub><ns0:mtext>G</ns0:mtext> <ns0:mn>2</ns0:mn></ns0:msub> </ns0:math> -structures.","authors":"Thomas A Ivey, Spiro Karigiannis","doi":"10.1007/s10711-024-00954-8","DOIUrl":"https://doi.org/10.1007/s10711-024-00954-8","url":null,"abstract":"<p><p>We consider the existence of cohomogeneity one solitons for the isometric flow of <math><msub><mtext>G</mtext> <mn>2</mn></msub> </math> -structures on the following classes of torsion-free <math><msub><mtext>G</mtext> <mn>2</mn></msub> </math> -manifolds: the Euclidean <math> <msup><mrow><mi>R</mi></mrow> <mn>7</mn></msup> </math> with its standard <math><msub><mtext>G</mtext> <mn>2</mn></msub> </math> -structure, metric cylinders over Calabi-Yau 3-folds, metric cones over nearly Kähler 6-manifolds, and the Bryant-Salamon <math><msub><mtext>G</mtext> <mn>2</mn></msub> </math> -manifolds. In all cases we establish existence of global solutions to the isometric soliton equations, and determine the asymptotic behaviour of the torsion. In particular, existence of shrinking isometric solitons on <math> <msup><mrow><mi>R</mi></mrow> <mn>7</mn></msup> </math> is proved, giving support to the likely existence of type I singularities for the isometric flow. In each case, the study of the soliton equation reduces to a particular nonlinear ODE with a regular singular point, for which we provide a careful analysis. Finally, to simplify the derivation of the relevant equations in each case, we first establish several useful Riemannian geometric formulas for a general class of cohomogeneity one metrics on total spaces of vector bundles which should have much wider application, as such metrics arise often as explicit examples of special holonomy metrics.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"218 5","pages":"102"},"PeriodicalIF":0.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11442535/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142367550","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Geometriae DedicataPub Date : 2024-01-01Epub Date: 2023-11-17DOI: 10.1007/s10711-023-00862-3
Michael Dymond, Vojtěch Kaluža
{"title":"Divergence of separated nets with respect to displacement equivalence.","authors":"Michael Dymond, Vojtěch Kaluža","doi":"10.1007/s10711-023-00862-3","DOIUrl":"https://doi.org/10.1007/s10711-023-00862-3","url":null,"abstract":"<p><p>We introduce a hierarchy of equivalence relations on the set of separated nets of a given Euclidean space, indexed by concave increasing functions <math><mrow><mi>ϕ</mi><mo>:</mo><mo>(</mo><mn>0</mn><mo>,</mo><mi>∞</mi><mo>)</mo><mo>→</mo><mo>(</mo><mn>0</mn><mo>,</mo><mi>∞</mi><mo>)</mo></mrow></math>. Two separated nets are called <math><mi>ϕ</mi></math>-<i>displacement equivalent</i> if, roughly speaking, there is a bijection between them which, for large radii <i>R</i>, displaces points of norm at most <i>R</i> by something of order at most <math><mrow><mi>ϕ</mi><mo>(</mo><mi>R</mi><mo>)</mo></mrow></math>. We show that the spectrum of <math><mi>ϕ</mi></math>-displacement equivalence spans from the established notion of <i>bounded displacement equivalence</i>, which corresponds to bounded <math><mi>ϕ</mi></math>, to the indiscrete equivalence relation, corresponding to <math><mrow><mi>ϕ</mi><mo>(</mo><mi>R</mi><mo>)</mo><mo>∈</mo><mi>Ω</mi><mo>(</mo><mi>R</mi><mo>)</mo></mrow></math>, in which all separated nets are equivalent. In between the two ends of this spectrum, the notions of <math><mi>ϕ</mi></math>-displacement equivalence are shown to be pairwise distinct with respect to the asymptotic classes of <math><mrow><mi>ϕ</mi><mo>(</mo><mi>R</mi><mo>)</mo></mrow></math> for <math><mrow><mi>R</mi><mo>→</mo><mi>∞</mi></mrow></math>. We further undertake a comparison of our notion of <math><mi>ϕ</mi></math>-displacement equivalence with previously studied relations on separated nets. Particular attention is given to the interaction of the notions of <math><mi>ϕ</mi></math>-displacement equivalence with that of <i>bilipschitz equivalence</i>.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"218 1","pages":"15"},"PeriodicalIF":0.5,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10656347/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138464551","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Knot groups, quandle extensions and orderability","authors":"Idrissa Ba, Mohamed Elhamdadi","doi":"10.1007/s10711-023-00876-x","DOIUrl":"https://doi.org/10.1007/s10711-023-00876-x","url":null,"abstract":"<p>This paper gives a new way of characterizing L-space 3-manifolds by using orderability of quandles. Hence, this answers a question of Clay et al. (Question 1.1 of Can Math Bull 59(3):472–482, 2016). We also investigate both the orderability and circular orderability of dynamical extensions of orderable quandles. We give conditions under which the conjugation quandle on a group, as an extension of the conjugation of a bi-orderable group by the conjugation of a right orderable group, is right orderable. We also study the right circular orderability of link quandles. We prove that the <i>n</i>-quandle <span>(Q_n(L))</span> of the link quandle of a link <i>L</i> in the 3-sphere is not right circularly orderable and hence it is not right orderable. But on the other hand, we show that there are infinitely many links for which the <i>p</i>-enveloping group of the link quandle is right circularly orderable for any prime integer <i>p</i>.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"25 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139061686","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}
Benjamin Brück, Francesco Fournier-Facio, Clara Löh
{"title":"Median quasimorphisms on $${{,mathrm{{CAT}},}}(0)$$ cube complexes and their cup products","authors":"Benjamin Brück, Francesco Fournier-Facio, Clara Löh","doi":"10.1007/s10711-023-00870-3","DOIUrl":"https://doi.org/10.1007/s10711-023-00870-3","url":null,"abstract":"<p>Cup products provide a natural approach to access higher bounded cohomology groups. We extend vanishing results on cup products of Brooks quasimorphisms of free groups to cup products of median quasimorphisms, i.e., Brooks-type quasimorphisms of group actions on <span>({{,mathrm{{CAT}},}}(0))</span> cube complexes. In particular, we obtain such vanishing results for groups acting on trees and for right-angled Artin groups. Moreover, we outline potential applications of vanishing results for cup products in bounded cohomology.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"89 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139029383","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":"Relations with a fixed interval exchange transformation","authors":"Magali Jay","doi":"10.1007/s10711-023-00868-x","DOIUrl":"https://doi.org/10.1007/s10711-023-00868-x","url":null,"abstract":"<h3>Abstract</h3> <p>We study the group of all interval exchange transformations (IETs). Katok asked whether it contains a free subgroup. We show that for every IET <em>S</em>, there exists a dense open set <span> <span>(Omega (S))</span> </span> of admissible IETs such that the group generated by <em>S</em> and any <span> <span>(Tin Omega (S))</span> </span> is not free of rank 2. This extends a result by Dahmani et al. (Groups Geom Dyn 7(4):883–910, 2013): the group generated by a generic pair of elements of IET([0;1)) is not free (assuming a suitable condition on the underlying permutation).</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"295 2 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138687579","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":"Correction: An improved bound on the optimal paper Moebius band","authors":"Richard Evan Schwartz","doi":"10.1007/s10711-023-00869-w","DOIUrl":"https://doi.org/10.1007/s10711-023-00869-w","url":null,"abstract":"","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"195 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138578926","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":"Moduli spaces of polygons and deformations of polyhedra with boundary","authors":"Sasha Anan’in, Dmitrii Korshunov","doi":"10.1007/s10711-023-00834-7","DOIUrl":"https://doi.org/10.1007/s10711-023-00834-7","url":null,"abstract":"<p>We prove a conjecture of Ian Agol: all isometric realizations of a polyhedral surface with boundary sweep out an isotropic subset in the Kapovich-Millson moduli space of polygons isomorphic to the boundary. For a generic polyhedral disk we show that boundaries of its isometric realizations make up a Lagrangian subset. As an application of this result, we conclude that a generic equilateral polygon cannot be domed (in the sense of a problem of Kenyon, Glazyrin and Pak).</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"10 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138578924","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":"Vanishing theorem on parabolic Kähler manifolds","authors":"Teng Huang","doi":"10.1007/s10711-023-00872-1","DOIUrl":"https://doi.org/10.1007/s10711-023-00872-1","url":null,"abstract":"<p>In this article, we consider the semipositive (resp. nef) line bundle on compact Kähler parabolic (resp. hyperbolic) manifolds. We prove some vanishing theorems for the <span>(L^{2})</span>-harmonic (<i>n</i>, <i>q</i>)-form of the holomorphic line bundles over complete Kähler manifolds.</p>","PeriodicalId":55103,"journal":{"name":"Geometriae Dedicata","volume":"21 1","pages":""},"PeriodicalIF":0.5,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138579028","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}