{"title":"On the Spielman-Teng Conjecture","authors":"Ashwin Sah, Julian Sahasrabudhe, Mehtaab Sawhney","doi":"10.1007/s00039-025-00707-z","DOIUrl":"https://doi.org/10.1007/s00039-025-00707-z","url":null,"abstract":"<p>Let <i>M</i> be an <i>n</i>×<i>n</i> matrix with iid subgaussian entries with mean 0 and variance 1 and let <i>σ</i><sub><i>n</i></sub>(<i>M</i>) denote the least singular value of <i>M</i>. We prove that </p><span>$$ mathbb{P}big( sigma _{n}(M) leqslant varepsilon n^{-1/2} big) = (1+o(1)) varepsilon + e^{- Omega (n)} $$</span><p> for all 0⩽<i>ε</i>≪1. This resolves, up to a 1+<i>o</i>(1) factor, a seminal conjecture of Spielman and Teng.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"62 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143401542","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}
{"title":"Geometric Langlands Duality for Periods","authors":"Tony Feng, Jonathan Wang","doi":"10.1007/s00039-025-00702-4","DOIUrl":"https://doi.org/10.1007/s00039-025-00702-4","url":null,"abstract":"<p>We study conjectures of Ben-Zvi–Sakellaridis–Venkatesh that categorify the relationship between automorphic periods and <i>L</i>-functions in the context of the Geometric Langlands equivalence. We provide evidence for these conjectures in some low-rank examples, by using derived Fourier analysis and the theory of chiral algebras to categorify the Rankin-Selberg unfolding method.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"26 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143192061","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}
{"title":"Optimal Rigidity and Maximum of the Characteristic Polynomial of Wigner Matrices","authors":"Paul Bourgade, Patrick Lopatto, Ofer Zeitouni","doi":"10.1007/s00039-025-00701-5","DOIUrl":"https://doi.org/10.1007/s00039-025-00701-5","url":null,"abstract":"<p>We determine to leading order the maximum of the characteristic polynomial for Wigner matrices and <i>β</i>-ensembles. In the special case of Gaussian-divisible Wigner matrices, our method provides universality of the maximum up to tightness. These are the first universal results on the Fyodorov–Hiary–Keating conjectures for these models, and in particular answer the question of optimal rigidity for the spectrum of Wigner matrices.</p><p>Our proofs combine dynamical techniques for universality of eigenvalue statistics with ideas surrounding the maxima of log-correlated fields and Gaussian multiplicative chaos.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"13 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143125161","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}
{"title":"Invariant Subvarieties of Minimal Homological Dimension, Zero Lyapunov Exponents, and Monodromy","authors":"Paul Apisa","doi":"10.1007/s00039-025-00700-6","DOIUrl":"https://doi.org/10.1007/s00039-025-00700-6","url":null,"abstract":"<p>We classify the <span>(mathrm{GL}(2,mathbb{R}))</span>-invariant subvarieties <span>(mathcal{M})</span> in strata of Abelian differentials for which any two <span>(mathcal{M})</span>-parallel cylinders have homologous core curves. As a corollary we show that outside of an explicit list of exceptions, if <span>(mathcal{M})</span> is a <span>(mathrm{GL}(2,mathbb{R}))</span>-invariant subvariety, then the Kontsevich-Zorich cocycle has nonzero Lyapunov exponents in the symplectic orthogonal of the projection of the tangent bundle of <span>(mathcal{M})</span> to absolute cohomology.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"22 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143077603","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}
{"title":"Unit and Distinct Distances in Typical Norms","authors":"Noga Alon, Matija Bucić, Lisa Sauermann","doi":"10.1007/s00039-025-00698-x","DOIUrl":"https://doi.org/10.1007/s00039-025-00698-x","url":null,"abstract":"<p>Erdős’ unit distance problem and Erdős’ distinct distances problem are among the most classical and well-known open problems in discrete mathematics. They ask for the maximum number of unit distances, or the minimum number of distinct distances, respectively, determined by <i>n</i> points in the Euclidean plane. The question of what happens in these problems if one considers normed spaces other than the Euclidean plane has been raised in the 1980s by Ulam and Erdős and attracted a lot of attention over the years. We give an essentially tight answer to both questions for almost all norms on <span>(mathbb{R}^{d})</span>, in a certain Baire categoric sense.</p><p>For the unit distance problem we prove that for almost all norms ∥.∥ on <span>(mathbb{R}^{d})</span>, any set of <i>n</i> points defines at most <span>(frac{1}{2} d cdot n log _{2} n)</span> unit distances according to ∥.∥. We also show that this is essentially tight, by proving that for <i>every</i> norm ∥.∥ on <span>(mathbb{R}^{d})</span>, for any large <i>n</i>, we can find <i>n</i> points defining at least <span>(frac{1}{2}(d-1-o(1))cdot n log _{2} n)</span> unit distances according to ∥.∥.</p><p>For the distinct distances problem, we prove that for almost all norms ∥.∥ on <span>(mathbb{R}^{d})</span> any set of <i>n</i> points defines at least (1−<i>o</i>(1))<i>n</i> distinct distances according to ∥.∥. This is clearly tight up to the <i>o</i>(1) term.</p><p>We also answer the famous Hadwiger–Nelson problem for almost all norms on <span>(mathbb{R}^{2})</span>, showing that their unit distance graph has chromatic number 4.</p><p>Our results settle, in a strong and somewhat surprising form, problems and conjectures of Brass, Matoušek, Brass–Moser–Pach, Chilakamarri, and Robertson. The proofs combine combinatorial and geometric ideas with tools from Linear Algebra, Topology and Algebraic Geometry.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"30 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143026658","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}
Michael Finkelberg, Victor Ginzburg, Roman Travkin
{"title":"Lagrangian Subvarieties of Hyperspherical Varieties","authors":"Michael Finkelberg, Victor Ginzburg, Roman Travkin","doi":"10.1007/s00039-025-00703-3","DOIUrl":"https://doi.org/10.1007/s00039-025-00703-3","url":null,"abstract":"<p>Given a hyperspherical <i>G</i>-variety 𝒳 we consider the zero moment level Λ<sub>𝒳</sub>⊂𝒳 of the action of a Borel subgroup <i>B</i>⊂<i>G</i>. We conjecture that Λ<sub>𝒳</sub> is Lagrangian. For the dual <i>G</i><sup>∨</sup>-variety 𝒳<sup>∨</sup>, we conjecture that that there is a bijection between the sets of irreducible components <span>(operatorname {Irr}Lambda _{{mathscr{X}}})</span> and <span>(operatorname {Irr}Lambda _{{mathscr{X}}^{vee }})</span>. We check this conjecture for all the hyperspherical equivariant slices, and for all the basic classical Lie superalgebras.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"28 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991959","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}
{"title":"Optimal Transport Between Algebraic Hypersurfaces","authors":"Paolo Antonini, Fabio Cavalletti, Antonio Lerario","doi":"10.1007/s00039-025-00699-w","DOIUrl":"https://doi.org/10.1007/s00039-025-00699-w","url":null,"abstract":"<p>What is the optimal way to deform a projective hypersurface into another one? In this paper we will answer this question adopting the point of view of measure theory, introducing the optimal transport problem between complex algebraic projective hypersurfaces.</p><p>First, a natural topological embedding of the space of hypersurfaces of a given degree into the space of measures on the projective space is constructed. Then, the optimal transport problem between hypersurfaces is defined through a constrained dynamical formulation, minimizing the energy of absolutely continuous curves which lie on the image of this embedding. In this way an inner Wasserstein distance on the projective space of homogeneous polynomials is introduced. This distance is finer than the Fubini–Study one.</p><p>The innner Wasserstein distance is complete and geodesic: geodesics corresponds to optimal deformations of one algebraic hypersurface into another one. Outside the discriminant this distance is induced by a smooth Riemannian metric, which is the real part of an explicit Hermitian structure. Moreover, this Hermitian structure is Kähler and the corresponding metric is of Weil–Petersson type.</p><p>To prove these results we develop new techniques, which combine complex and symplectic geometry with optimal transport, and which we expect to be relevant on their own.</p><p>We discuss applications on the regularity of the zeroes of a family of multivariate polynomials and on the condition number of polynomial systems solving.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"27 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142991957","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}
{"title":"On the Distance Sets Spanned by Sets of Dimension d/2 in $mathbb{R}^{d}$","authors":"Pablo Shmerkin, Hong Wang","doi":"10.1007/s00039-024-00696-5","DOIUrl":"https://doi.org/10.1007/s00039-024-00696-5","url":null,"abstract":"<p>We establish the dimension version of Falconer’s distance set conjecture for sets of equal Hausdorff and packing dimension (in particular, for Ahlfors-regular sets) in all ambient dimensions. In dimensions <i>d</i>=2 or 3, we obtain the first explicit improvements over the classical 1/2 bound for the dimensions of distance sets of general Borel sets of dimension <i>d</i>/2. For example, we show that the set of distances spanned by a planar Borel set of Hausdorff dimension 1 has Hausdorff dimension at least <span>((sqrt{5}-1)/2approx 0.618)</span>. In higher dimensions we obtain explicit estimates for the lower Minkowski dimension of the distance sets of sets of dimension <i>d</i>/2. These results rely on new estimates for the dimensions of radial projections that may have independent interest.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"8 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937627","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}
{"title":"The Hadwiger Theorem on Convex Functions, I","authors":"Andrea Colesanti, Monika Ludwig, Fabian Mussnig","doi":"10.1007/s00039-024-00693-8","DOIUrl":"https://doi.org/10.1007/s00039-024-00693-8","url":null,"abstract":"<p>A complete classification of all continuous, epi-translation and rotation invariant valuations on the space of super-coercive convex functions on <span>({mathbb{R}}^{n})</span> is established. The valuations obtained are functional versions of the classical intrinsic volumes. For their definition, singular Hessian valuations are introduced.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"24 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142439713","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}
{"title":"Geometric Regularity of Blow-up Limits of the Kähler-Ricci Flow","authors":"Max Hallgren, Wangjian Jian, Jian Song, Gang Tian","doi":"10.1007/s00039-024-00694-7","DOIUrl":"https://doi.org/10.1007/s00039-024-00694-7","url":null,"abstract":"<p>We establish geometric regularity for Type I blow-up limits of the Kähler-Ricci flow based at any sequence of Ricci vertices. As a consequence, the limiting flow is continuous in time in both Gromov-Hausdorff and Gromov-<i>W</i><sub>1</sub> distances. In particular, the singular sets of each time slice and its tangent cones are closed and of codimension no less than 4.</p>","PeriodicalId":12478,"journal":{"name":"Geometric and Functional Analysis","volume":"169 1","pages":""},"PeriodicalIF":2.2,"publicationDate":"2024-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142439806","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}