Ajay Chandra, Guilherme de Lima Feltes, Hendrik Weber
We show a priori bounds for solutions to in finite volume in the framework of Hairer's Regularity Structures [Invent Math 198:269–504, 2014]. We assume and that is of negative Hölder regularity of order where for an explicit , and that it can be lifted to a model in the sense of Regularity Structures. Our main results guarantee non‐explosion of the solution in finite time and a growth, which is at most polynomial in . Our estimates imply global well‐posedness for the 2‐d generalised parabolic Anderson model on the torus, as well as for the parabolic quantisation of the Sine–Gordon Euclidean quantum fieldtheory (EQFT) on the torus in the regime . We also consider the parabolic quantisation of a massive Sine–Gordon EQFT and derive estimates that imply the existence of the measure for the same range of . Finally, our estimates apply to Itô SPDEs in the sense of Da Prato‐Zabczyk [ Stochastic Equations in Infinite Dimensions , Enc. Math. App., Cambridge Univ. Press, 1992] and imply existence of a stochastic flow beyond the trace‐class regime.
{"title":"A priori bounds for the generalised parabolic Anderson model","authors":"Ajay Chandra, Guilherme de Lima Feltes, Hendrik Weber","doi":"10.1002/cpa.70025","DOIUrl":"https://doi.org/10.1002/cpa.70025","url":null,"abstract":"We show a priori bounds for solutions to in finite volume in the framework of Hairer's Regularity Structures [Invent Math 198:269–504, 2014]. We assume and that is of negative Hölder regularity of order where for an explicit , and that it can be lifted to a model in the sense of Regularity Structures. Our main results guarantee non‐explosion of the solution in finite time and a growth, which is at most polynomial in . Our estimates imply global well‐posedness for the 2‐d generalised parabolic Anderson model on the torus, as well as for the parabolic quantisation of the Sine–Gordon Euclidean quantum fieldtheory (EQFT) on the torus in the regime . We also consider the parabolic quantisation of a massive Sine–Gordon EQFT and derive estimates that imply the existence of the measure for the same range of . Finally, our estimates apply to Itô SPDEs in the sense of Da Prato‐Zabczyk [ <jats:italic>Stochastic Equations in Infinite Dimensions</jats:italic> , Enc. Math. App., Cambridge Univ. Press, 1992] and imply existence of a stochastic flow beyond the trace‐class regime.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"120 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145955151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We show that any open set that is a finite distance away from a Lipschitz subgraph will become a Lipschitz subgraph after flowing under fractional mean curvature flow for a finite, universal time. Our proof is quantitative and inherently nonlocal, as the corresponding statement is false for classical mean curvature flow. This is the first regularizing effect proven for weak solutions to nonlocal curvature flow.
{"title":"Eventual regularization of fractional mean curvature flow","authors":"Stephen Cameron","doi":"10.1002/cpa.70028","DOIUrl":"https://doi.org/10.1002/cpa.70028","url":null,"abstract":"We show that any open set that is a finite distance away from a Lipschitz subgraph will become a Lipschitz subgraph after flowing under fractional mean curvature flow for a finite, universal time. Our proof is quantitative and inherently nonlocal, as the corresponding statement is false for classical mean curvature flow. This is the first regularizing effect proven for weak solutions to nonlocal curvature flow.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"38 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145955149","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We show that a complete contractible 3‐manifold with positive scalar curvature and bounded geometry must be . We also show that an open handlebody of genus larger than 1 does not admit complete metrics with positive scalar curvature and bounded geometry. Our results rely on the maximal weak solution to inverse mean curvature flow due to the third‐named author.
{"title":"3‐Manifolds With Positive Scalar Curvature and Bounded Geometry","authors":"Otis Chodosh, Yi Lai, Kai Xu","doi":"10.1002/cpa.70029","DOIUrl":"https://doi.org/10.1002/cpa.70029","url":null,"abstract":"We show that a complete contractible 3‐manifold with positive scalar curvature and bounded geometry must be . We also show that an open handlebody of genus larger than 1 does not admit complete metrics with positive scalar curvature and bounded geometry. Our results rely on the maximal weak solution to inverse mean curvature flow due to the third‐named author.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"4 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2026-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145937959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We develop a new degree theory for 4‐dimensional, asymptotically conical gradient expanding solitons. Our theory implies the existence of gradient expanding solitons that are asymptotic to any given cone over with non‐negative scalar curvature. We also obtain a similar existence result for cones whose link is diffeomorphic to if we allow the expanding soliton to have orbifold singularities. Our theory reveals the existence of a new topological invariant, called the expander degree , applicable to a particular class of compact, smooth 4‐orbifolds with boundary. This invariant is roughly equal to a signed count of all possible gradient expanding solitons that can be defined on the interior of the orbifold and are asymptotic to any fixed cone metric with non‐negative scalar curvature. If the expander degree of an orbifold is non‐zero, then gradient expanding solitons exist for any such cone metric. We show that the expander degree of the 4‐disk and any orbifold of the form equals 1. Additionally, we demonstrate that the expander degree of certain orbifolds, including exotic 4‐disks, vanishes. Our theory also sheds light on the relation between gradient and non‐gradient expanding solitons with respect to their asymptotic model. More specifically, we show that among the set of asymptotically conical expanding solitons, the subset of those solitons that are gradient forms a union of connected components.
{"title":"Degree theory for 4‐dimensional asymptotically conical gradient expanding solitons","authors":"Richard H. Bamler, Eric Chen","doi":"10.1002/cpa.70024","DOIUrl":"https://doi.org/10.1002/cpa.70024","url":null,"abstract":"We develop a new degree theory for 4‐dimensional, asymptotically conical gradient expanding solitons. Our theory implies the existence of gradient expanding solitons that are asymptotic to any given cone over with non‐negative scalar curvature. We also obtain a similar existence result for cones whose link is diffeomorphic to if we allow the expanding soliton to have orbifold singularities. Our theory reveals the existence of a new topological invariant, called the <jats:italic>expander degree</jats:italic> , applicable to a particular class of compact, smooth 4‐orbifolds with boundary. This invariant is roughly equal to a signed count of all possible gradient expanding solitons that can be defined on the interior of the orbifold and are asymptotic to any fixed cone metric with non‐negative scalar curvature. If the expander degree of an orbifold is non‐zero, then gradient expanding solitons exist for any such cone metric. We show that the expander degree of the 4‐disk and any orbifold of the form equals 1. Additionally, we demonstrate that the expander degree of certain orbifolds, including exotic 4‐disks, vanishes. Our theory also sheds light on the relation between gradient and non‐gradient expanding solitons with respect to their asymptotic model. More specifically, we show that among the set of asymptotically conical expanding solitons, the subset of those solitons that are <jats:italic>gradient</jats:italic> forms a union of connected components.","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"66 1","pages":""},"PeriodicalIF":3.0,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145759574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sébastien Boucksom, Mattias Jonsson, Antonio Trusiani
Generalizing previous results of Arezzo–Pacard–Singer, Seyyedali–Székelyhidi, and Hallam, we prove the invariance under smooth blowups of the class of weighted extremal Kähler manifolds, modulo a log-concavity assumption on the first weight. Through recent work of Di Nezza–Jubert–Lahdili and Han–Liu, this is obtained as a consequence of a general uniform coercivity estimate for the (relative, weighted) Mabuchi energy on the blowup, which applies more generally to any equivariant resolution of singularities of Fano type of a compact Kähler klt space whose Mabuchi energy is assumed to be coercive.
推广了Arezzo-Pacard-Singer, seyyedali - sz kelyhidi, and Hallam之前的结果,证明了一类加权极值Kähler流形在光滑膨胀下的不变性,在第一权值上取对数凹性的模。通过Di Nezza-Jubert-Lahdili和Han-Liu最近的工作,这是作为(相对的,加权的)Mabuchi能量在blowup上的一般均匀矫顽力估计的结果得到的,它更普遍地适用于紧化Kähler klt空间的Fano型奇点的任何等变分辨率,其中Mabuchi能量被假设为矫顽力。
{"title":"Weighted extremal kähler metrics on resolutions of singularities","authors":"Sébastien Boucksom, Mattias Jonsson, Antonio Trusiani","doi":"10.1002/cpa.70026","DOIUrl":"10.1002/cpa.70026","url":null,"abstract":"<p>Generalizing previous results of Arezzo–Pacard–Singer, Seyyedali–Székelyhidi, and Hallam, we prove the invariance under smooth blowups of the class of weighted extremal Kähler manifolds, modulo a log-concavity assumption on the first weight. Through recent work of Di Nezza–Jubert–Lahdili and Han–Liu, this is obtained as a consequence of a general uniform coercivity estimate for the (relative, weighted) Mabuchi energy on the blowup, which applies more generally to any equivariant resolution of singularities of Fano type of a compact Kähler klt space whose Mabuchi energy is assumed to be coercive.</p>","PeriodicalId":10601,"journal":{"name":"Communications on Pure and Applied Mathematics","volume":"79 4","pages":"1073-1148"},"PeriodicalIF":2.7,"publicationDate":"2025-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145673663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<p>We study isoperimetric inequalities on “slabs”, namely weighted Riemannian manifolds obtained as the product of the uniform measure on a finite length interval with a codimension-one base. As our two main applications, we consider the case when the base is the flat torus <span></span><math>