{"title":"On the closability of differential operators","authors":"Giovanni Alberti , David Bate , Andrea Marchese","doi":"10.1016/j.jfa.2025.111029","DOIUrl":"10.1016/j.jfa.2025.111029","url":null,"abstract":"<div><div>We discuss the closability of directional derivative operators with respect to a general Radon measure <em>μ</em> on <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup></math></span>; our main theorem completely characterizes the vectorfields for which the corresponding operator is closable from the space of Lipschitz functions <span><math><mrow><mi>Lip</mi></mrow><mo>(</mo><msup><mrow><mi>R</mi></mrow><mrow><mi>d</mi></mrow></msup><mo>)</mo></math></span> to <span><math><msup><mrow><mi>L</mi></mrow><mrow><mi>p</mi></mrow></msup><mo>(</mo><mi>μ</mi><mo>)</mo></math></span>, for <span><math><mn>1</mn><mo>≤</mo><mi>p</mi><mo>≤</mo><mo>∞</mo></math></span>. We also discuss the closability of the same operators from <span><math><msup><mrow><mi>L</mi></mrow><mrow><mi>q</mi></mrow></msup><mo>(</mo><mi>μ</mi><mo>)</mo></math></span> to <span><math><msup><mrow><mi>L</mi></mrow><mrow><mi>p</mi></mrow></msup><mo>(</mo><mi>μ</mi><mo>)</mo></math></span>, and give necessary and sufficient conditions for closability, but we do not have an exact characterization.</div><div>As a corollary we obtain that classical differential operators such as gradient, divergence and Jacobian determinant are closable from <span><math><msup><mrow><mi>L</mi></mrow><mrow><mi>q</mi></mrow></msup><mo>(</mo><mi>μ</mi><mo>)</mo></math></span> to <span><math><msup><mrow><mi>L</mi></mrow><mrow><mi>p</mi></mrow></msup><mo>(</mo><mi>μ</mi><mo>)</mo></math></span> only if <em>μ</em> is absolutely continuous with respect to the Lebesgue measure.</div><div>We finally consider the closability of a certain class of multilinear differential operators; these results are then rephrased in terms of metric currents.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 7","pages":"Article 111029"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923573","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 continuity of Følner averages","authors":"Gabriel Fuhrmann , Maik Gröger , Till Hauser","doi":"10.1016/j.jfa.2025.111039","DOIUrl":"10.1016/j.jfa.2025.111039","url":null,"abstract":"<div><div>It is known that if each point <em>x</em> of a dynamical system is generic for some invariant measure <span><math><msub><mrow><mi>μ</mi></mrow><mrow><mi>x</mi></mrow></msub></math></span>, then there is a strong connection between certain ergodic and topological properties of that system. In particular, if the acting group is abelian and the map <span><math><mi>x</mi><mo>↦</mo><msub><mrow><mi>μ</mi></mrow><mrow><mi>x</mi></mrow></msub></math></span> is continuous, then every orbit closure is uniquely ergodic.</div><div>In this note, we show that if the acting group is not abelian, orbit closures may well support more than one ergodic measure even if <span><math><mi>x</mi><mo>↦</mo><msub><mrow><mi>μ</mi></mrow><mrow><mi>x</mi></mrow></msub></math></span> is continuous. We provide examples of such a situation via actions of the group of all orientation-preserving homeomorphisms on the unit interval as well as the Lamplighter group. To discuss these examples, we need to extend the existing theory of weakly mean equicontinuous group actions to allow for multiple ergodic measures on orbit closures and to allow for actions of general amenable groups. These extensions are achieved by adopting an operator-theoretic approach.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 7","pages":"Article 111039"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143942789","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":"The free elastic flow for closed planar curves","authors":"Tatsuya Miura , Glen Wheeler","doi":"10.1016/j.jfa.2025.111030","DOIUrl":"10.1016/j.jfa.2025.111030","url":null,"abstract":"<div><div>The free elastic flow is the <span><math><msup><mrow><mi>L</mi></mrow><mrow><mn>2</mn></mrow></msup></math></span>-gradient flow for Euler's elastic energy, or equivalently the Willmore flow with translation invariant initial data. In contrast to elastic flows under length penalisation or preservation, it is more challenging to study the free elastic flow's asymptotic behaviour, and convergence for closed curves is lost. In this paper, we nevertheless determine the asymptotic shape of the flow for initial curves that are geometrically close to circles, possibly multiply-covered, proving that an appropriate rescaling smoothly converges to a unique round circle.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 7","pages":"Article 111030"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143903730","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":"Type II singularities of Lagrangian mean curvature flow with zero Maslov class","authors":"Xiang Li , Yong Luo , Jun Sun","doi":"10.1016/j.jfa.2025.111032","DOIUrl":"10.1016/j.jfa.2025.111032","url":null,"abstract":"<div><div>In this paper, we will prove some rigidity theorems for blow up limits to Type II singularities of Lagrangian mean curvature flow with zero Maslov class or almost calibrated Lagrangian mean curvature flows, especially for Lagrangian translating solitons in arbitrary dimension. These theorems generalized previous corresponding results from two dimensional case to arbitrarily dimensional case.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 6","pages":"Article 111032"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143904065","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":"The Helton-Howe trace formula for the Drury-Arveson space","authors":"Jingbo Xia","doi":"10.1016/j.jfa.2025.111037","DOIUrl":"10.1016/j.jfa.2025.111037","url":null,"abstract":"<div><div>The famous Helton-Howe trace formula was originally established for antisymmetric sums of Toeplitz operators on the Bergman space of the unit ball. We prove the analogue of this formula on the Drury-Arveson space.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 7","pages":"Article 111037"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923570","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":"The Cauchy problem for the quadratic beam equation in d ≥ 2","authors":"Zihao Song","doi":"10.1016/j.jfa.2025.111041","DOIUrl":"10.1016/j.jfa.2025.111041","url":null,"abstract":"<div><div>The purpose of this paper is to study the Cauchy problem of the beam equation with quadratic nonlinearity. We establish the global well-posedness and scattering of small solutions in <span><math><mn>2</mn><mo>≤</mo><mi>d</mi><mo>≤</mo><mn>8</mn></math></span> with the strategy of Strichartz estimates, dispersive estimates and the method of space-time resonance. The main difficulties come from the weak dispersive estimates of beam semi-group and possible resonance. We shall utilize the observation of null structure for space-time resonance, which enables us to obtain enough decay but avoiding the degeneracies.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 7","pages":"Article 111041"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923569","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 equivalence of distributional and synthetic Ricci curvature lower bounds","authors":"Andrea Mondino, Vanessa Ryborz","doi":"10.1016/j.jfa.2025.111035","DOIUrl":"10.1016/j.jfa.2025.111035","url":null,"abstract":"<div><div>The goal of the paper is to prove the equivalence of distributional and synthetic Ricci curvature lower bounds for a weighted Riemannian manifold with continuous metric tensor having Christoffel symbols in <span><math><msubsup><mrow><mi>L</mi></mrow><mrow><mi>loc</mi></mrow><mrow><mn>2</mn></mrow></msubsup></math></span>, and with weight in <span><math><msup><mrow><mi>C</mi></mrow><mrow><mn>0</mn></mrow></msup><mo>∩</mo><msubsup><mrow><mi>W</mi></mrow><mrow><mi>loc</mi></mrow><mrow><mn>1</mn><mo>,</mo><mn>2</mn></mrow></msubsup></math></span>.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 8","pages":"Article 111035"},"PeriodicalIF":1.7,"publicationDate":"2025-04-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923472","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":"Functional calculus of quantum channels for the holomorphic discrete series of SU(1,1)","authors":"Robin van Haastrecht","doi":"10.1016/j.jfa.2025.111036","DOIUrl":"10.1016/j.jfa.2025.111036","url":null,"abstract":"<div><div>The tensor product of two holomorphic discrete series representations of <span><math><mi>S</mi><mi>U</mi><mo>(</mo><mn>1</mn><mo>,</mo><mn>1</mn><mo>)</mo></math></span> can be decomposed as a direct multiplicity-free sum of infinitely many holomorphic discrete series representations. I shall introduce equivariant quantum channels for each component of the direct sum by mapping the tensor product of an operator and the identity onto the projection onto one of the irreducible components, generalizing the construction of pure equivariant quantum channels for compact groups. Then I calculate the functional calculus of this operator for polynomials and prove a limit formula for the trace of the functional calculus for any differentiable function. The methods I used are the theory of reproducing kernel Hilbert spaces and a Plancherel theorem for the disk <span><math><mi>D</mi><mo>=</mo><mi>S</mi><mi>U</mi><mo>(</mo><mn>1</mn><mo>,</mo><mn>1</mn><mo>)</mo><mo>/</mo><mi>U</mi><mo>(</mo><mn>1</mn><mo>)</mo></math></span>, together with exact constants for the eigenvalues of the Berezin transform. I prove that the limit of the trace of the functional calculus can be expressed using generalized Husimi functions or using Berezin transforms.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 6","pages":"Article 111036"},"PeriodicalIF":1.7,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143907574","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}
Michael Lacey , Ji Li , Brett D. Wick , Liangchuan Wu
{"title":"Schatten classes and commutators of Riesz transforms in the two weight setting","authors":"Michael Lacey , Ji Li , Brett D. Wick , Liangchuan Wu","doi":"10.1016/j.jfa.2025.111028","DOIUrl":"10.1016/j.jfa.2025.111028","url":null,"abstract":"<div><div>We characterize the Schatten class <span><math><msup><mrow><mi>S</mi></mrow><mrow><mi>p</mi></mrow></msup></math></span> of the commutator of Riesz transforms <span><math><mo>[</mo><mi>b</mi><mo>,</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>]</mo></math></span> in <span><math><msup><mrow><mi>R</mi></mrow><mrow><mi>n</mi></mrow></msup></math></span> (<span><math><mi>j</mi><mo>=</mo><mn>1</mn><mo>,</mo><mo>…</mo><mo>,</mo><mi>n</mi></math></span>) in the two weight setting for <span><math><mi>n</mi><mo><</mo><mi>p</mi><mo><</mo><mo>∞</mo></math></span>, by introducing the condition that the symbol <em>b</em> is in Besov spaces associated with the given two weights. At the critical index <span><math><mi>p</mi><mo>=</mo><mi>n</mi></math></span>, the commutator <span><math><mo>[</mo><mi>b</mi><mo>,</mo><msub><mrow><mi>R</mi></mrow><mrow><mi>j</mi></mrow></msub><mo>]</mo></math></span> belongs to Schatten class <span><math><msup><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msup></math></span> if and only if <em>b</em> is a constant, and to the weak Schatten class <span><math><msup><mrow><mi>S</mi></mrow><mrow><mi>n</mi><mo>,</mo><mo>∞</mo></mrow></msup></math></span> if and only if <em>b</em> is in an oscillation sequence space associated with the given two weights. As a direct application, we have the Schatten class estimate for A. Connes' quantized derivative in the two weight setting.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 6","pages":"Article 111028"},"PeriodicalIF":1.7,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143907575","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}
Tristan Bice , Lisa Orloff Clark , Ying-Fen Lin , Kathryn McCormick
{"title":"Cartan semigroups and twisted groupoid C*-algebras","authors":"Tristan Bice , Lisa Orloff Clark , Ying-Fen Lin , Kathryn McCormick","doi":"10.1016/j.jfa.2025.111038","DOIUrl":"10.1016/j.jfa.2025.111038","url":null,"abstract":"<div><div>We prove that twisted groupoid C*-algebras are characterised, up to isomorphism, by having <em>Cartan semigroups</em>, a natural generalisation of normaliser semigroups of Cartan subalgebras. This extends the classic Kumjian-Renault theory to general twisted étale groupoid C*-algebras, even non-reduced C*-algebras of non-effective groupoids.</div></div>","PeriodicalId":15750,"journal":{"name":"Journal of Functional Analysis","volume":"289 7","pages":"Article 111038"},"PeriodicalIF":1.7,"publicationDate":"2025-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143923572","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}