{"title":"Fractal uncertainty principle for discrete Cantor sets with random alphabets","authors":"Suresh Eswarathasan, Xiaolong Han","doi":"10.4310/mrl.2023.v30.n6.a2","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n6.a2","url":null,"abstract":"In this paper, we investigate the fractal uncertainty principle (FUP) for discrete Cantor sets, which are determined by an alphabet from a base of digits. Consider the base of $M$ digits and the alphabets of cardinality $A$ such that all the corresponding Cantor sets have a fixed dimension $log A/log Min (0,2/3)$. We prove that the FUP with an improved exponent over Dyatlov-Jin $href{https://doi.org/10.48550/arXiv.2107.08276}{textrm{DJ-1}}$ holds for almost all alphabets, asymptotically as $Mtoinfty$. Our result provides the best possible exponent when the Cantor sets enjoy either the strongest Fourier decay assumption or strongest additive energy assumption. The proof is based on a concentration of measure phenomenon in the space of alphabets.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"36 Suppl 2 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141744903","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On radical filtrations of parabolic Verma modules","authors":"Jun Hu, Wei Xiao","doi":"10.4310/mrl.2023.v30.n5.a7","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a7","url":null,"abstract":"In this paper we give a sum formula for the radical filtration of parabolic Verma modules in any (possibly singular) blocks of parabolic BGG category. It can be viewed as a generalization of the Jantzen sum formula for Verma modules in the usual BGG category $mathcal{O}$. The proof makes use of the graded version of parabolic BGG category. Explicit formulae for the graded decomposition numbers and inverse graded decomposition numbers of parabolic Verma modules in any (possibly singular) integral blocks of the parabolic BGG category are also given in terms of the Kazhdan–Lusztig polynomials.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"47 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941577","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"$H^s$ bounds for the derivative nonlinear Schrödinger equation","authors":"Hajer Bahouri, Trevor M. Leslie, Galina Perelman","doi":"10.4310/mrl.2023.v30.n5.a1","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a1","url":null,"abstract":"We study the derivative nonlinear Schrödinger equation on the real line and obtain global-in-time bounds on high order Sobolev norms.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"27 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A note on five dimensional kissing arrangements","authors":"Ferenc Szöllősi","doi":"10.4310/mrl.2023.v30.n5.a13","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a13","url":null,"abstract":"The kissing number $tau (d)$ is the maximum number of pairwise non-overlapping unit spheres each touching a central unit sphere in the $d$-dimensional Euclidean space. In this note we report on how we discovered a new, previously unknown arrangement of 40 unit spheres in dimension $5$. Our arrangement saturates the best known lower bound on $tau (5)$, and refutes a ‘belief’ of Cohn–Jiao–Kumar–Torquato.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"77 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941576","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Finiteness of non-constant maps over a number field","authors":"Ariyan Javanpeykar","doi":"10.4310/mrl.2023.v30.n5.a9","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a9","url":null,"abstract":"Motivated by the intermediate Lang conjectures on hyperbolicity and rational points, we prove new finiteness results for non-constant morphisms from a fixed variety to a fixed variety defined over a number field by applying Faltings’s finiteness results to moduli spaces of maps.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"19 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941585","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Partial data inverse problems for nonlinear magnetic Schrödinger equations","authors":"Ru-Yu Lai, Ting Zhou","doi":"10.4310/mrl.2023.v30.n5.a10","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a10","url":null,"abstract":"We prove that the knowledge of the Dirichlet-to-Neumann map, measured on a part of the boundary of a bounded domain in $mathbb{R}^n , n geq 2$, can uniquely determine, in a nonlinear magnetic Schrödinger equation, the vector-valued magnetic potential and the scalar electric potential, both being nonlinear in the solution.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"25 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941504","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Deformations of $log$ Calabi–Yau pairs can be obstructed","authors":"Simon Felten, Andrea Petracci, Sharon Robins","doi":"10.4310/mrl.2023.v30.n5.a3","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a3","url":null,"abstract":"We exhibit examples of pairs $(X,D)$ where $X$ is a smooth projective variety and $D$ is an anticanonical reduced simple normal crossing divisor such that the deformations of $(X,D)$ are obstructed. These examples are constructed via toric geometry.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"65 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941580","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Improved discrete restriction for the parabola","authors":"Shaoming Guo, Zane Kun Li, Po-Lam Yung","doi":"10.4310/mrl.2023.v30.n5.a4","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a4","url":null,"abstract":"Using ideas from $href{https://doi.org/10.4171/jems/1295}{[7]}$ and working over $mathbb{Q}_p$, we show that the discrete restriction constant for the parabola is $O_varepsilon ((log M)^{2+varepsilon})$.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"22 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941574","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"On certain extensions of vector bundles in $p$-adic geometry","authors":"Serin Hong","doi":"10.4310/mrl.2023.v30.n5.a6","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a6","url":null,"abstract":"Given two arbitrary vector bundles on the Fargues–Fontaine curve, we give an explicit criterion in terms of Harder–Narasimhan polygons on whether they realize a semistable vector bundle as their extensions. Our argument is largely combinatorial and builds upon the dimension analysis of certain moduli spaces of bundle maps developed in $href{https://doi.org/10.1017/S1474748020000183}{[1]}$.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"28 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Ribbon cobordisms as a partial order","authors":"Marius Huber","doi":"10.4310/mrl.2023.v30.n5.a8","DOIUrl":"https://doi.org/10.4310/mrl.2023.v30.n5.a8","url":null,"abstract":"We show that the notion of ribbon rational homology cobordism yields a partial order on the set of aspherical 3‑manifolds, thus supporting a conjecture formulated by Daemi, Lidman, Vela–Vick and Wong. Our proof is built on Agol’s recent proof of the fact that ribbon concordance yields a partial order on the set of knots in the 3‑sphere.","PeriodicalId":49857,"journal":{"name":"Mathematical Research Letters","volume":"41 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140941455","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}