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Framed motives of algebraic varieties (after V. Voevodsky) J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-12-03 Grigory Garkusha; Ivan Panin
Abstract:A new approach to stable motivic homotopy theory is given. It is based on Voevodsky's theory of framed correspondences. Using the theory, framed motives of algebraic varieties are introduced and studied in the paper. They are the major computational tool for constructing an explicit quasi-fibrant motivic replacement of the suspension -spectrum of any smooth scheme . Moreover, it is shown that
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Non-concentration of the chromatic number of a random graph J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-12-03 Annika Heckel
Abstract:We show that the chromatic number of is not concentrated on fewer than consecutive values. This addresses a longstanding question raised by Erdős and several other authors.
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A sequence of polynomials with optimal condition number J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-12-08 Carlos Beltrán; Ujué Etayo; Jordi Marzo; Joaquim Ortega-Cerdà
Abstract:We find an explicit sequence of univariate polynomials of arbitrary degree with optimal condition number. This solves a problem posed by Michael Shub and Stephen Smale in 1993.
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The test function conjecture for parahoric local models J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-12-07 Thomas Haines; Timo Richarz
Abstract:We prove the test function conjecture of Kottwitz and the first-named author for local models of Shimura varieties with parahoric level structure, and their analogues in equal characteristic.
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Elliptic stable envelopes J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-12-09 Mina Aganagic; Andrei Okounkov
Abstract:We construct stable envelopes in equivariant elliptic cohomology of Nakajima quiver varieties. In particular, this gives an elliptic generalization of the results of Maulik and Okounkov [Astérisque 408 (2019), ix+209]. We apply them to the computation of the monodromy of -difference equations arising in the enumerative K-theory of rational curves in Nakajima varieties, including the quantum
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Cartier modules and cyclotomic spectra J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-12-02 Benjamin Antieau; Thomas Nikolaus
Abstract:We construct and study a -structure on -typical cyclotomic spectra and explain how to recover crystalline cohomology of smooth schemes over perfect fields using this -structure. Our main tool is a new approach to -typical cyclotomic spectra via objects we call -typical topological Cartier modules. Using these, we prove that the heart of the cyclotomic -structure is the full subcategory of
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Virtual homological spectral radii for automorphisms of surfaces J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-08-19 Yi Liu
Abstract:In this paper, it is shown that any surface automorphism of positive mapping-class entropy possesses a virtual homological eigenvalue which lies outside the unit circle of the complex plane.
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Nonuniqueness and mean-field criticality for percolation on nonunimodular transitive graphs J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-09-23 Tom Hutchcroft
Abstract:We study Bernoulli bond percolation on nonunimodular quasi-transitive graphs, and more generally graphs whose automorphism group has a nonunimodular quasi-transitive subgroup. We prove that percolation on any such graph has a nonempty phase in which there are infinite light clusters, which implies the existence of a nonempty phase in which there are infinitely many infinite clusters. That
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Bounds on 2-torsion in class groups of number fields and integral points on elliptic curves J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-08-28 M. Bhargava; A. Shankar; T. Taniguchi; F. Thorne; J. Tsimerman; Y. Zhao
Abstract:We prove the first known nontrivial bounds on the sizes of the 2-torsion subgroups of the class groups of cubic and higher degree number fields (the trivial bound being coming from the bound on the entire class group). This yields corresponding improvements to: (1) bounds of Brumer and Kramer on the sizes of 2-Selmer groups and ranks of elliptic curves, (2) bounds of Helfgott and Venkatesh
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Examples of compact Einstein four-manifolds with negative curvature J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-09-14 Joel Fine; Bruno Premoselli
Abstract:We give new examples of compact, negatively curved Einstein manifolds of dimension . These are seemingly the first such examples which are not locally homogeneous. Our metrics are carried by a sequence of four-manifolds previously considered by Gromov and Thurston (Pinching constants for hyperbolic manifolds, Invent. Math. 89 (1987), no. 1, 1-12). The construction begins with a certain sequence
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Large genus asymptotics for volumes of strata of abelian differentials J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-09-28 Amol Aggarwal
Abstract:In this paper we consider the large genus asymptotics for Masur-Veech volumes of arbitrary strata of Abelian differentials. Through a combinatorial analysis of an algorithm proposed in 2002 by Eskin-Okounkov to exactly evaluate these quantities, we show that the volume of a stratum indexed by a partition is , as tends to . This confirms a prediction of Eskin-Zorich and generalizes some of
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Tame topology of arithmetic quotients and algebraicity of Hodge loci J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-09-15 B. Bakker; B. Klingler; J. Tsimerman
Abstract:In this paper we prove the following results: We show that any arithmetic quotient of a homogeneous space admits a natural real semi-algebraic structure for which its Hecke correspondences are semi-algebraic. A particularly important example is given by Hodge varieties, which parametrize pure polarized integral Hodge structures. We prove that the period map associated to any pure polarized
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Pacman renormalization and self-similarity of the Mandelbrot set near Siegel parameters J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-06-16 Dzmitry Dudko; Mikhail Lyubich; Nikita Selinger
Abstract:In the 1980s Branner and Douady discovered a surgery relating various limbs of the Mandelbrot set. We put this surgery in the framework of ``Pacman Renormalization Theory'' that combines features of quadratic-like and Siegel renormalizations. We show that Siegel renormalization periodic points (constructed by McMullen in the 1990s) can be promoted to pacman renormalization periodic points
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The 4-dimensional light bulb theorem J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-06-15 David Gabai
Abstract:For embedded 2-spheres in a 4-manifold sharing the same embedded transverse sphere homotopy implies isotopy, provided the ambient 4-manifold has no -torsion in the fundamental group. This gives a generalization of the classical light bulb trick to 4-dimensions, the uniqueness of spanning discs for a simple closed curve in and . In manifolds with -torsion, one surface can be put into a normal
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Geometric stabilisation via 𝑝-adic integration J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-06-15 Michael Groechenig; Dimitri Wyss; Paul Ziegler
Abstract:In this article we give a new proof of Ngô's geometric stabilisation theorem, which implies the fundamental lemma. This is a statement which relates the cohomology of Hitchin fibres for a quasi-split reductive group scheme to the cohomology of Hitchin fibres for the endoscopy groups . Our proof avoids the decomposition and support theorem, instead the argument is based on results for -adic
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Symplectic topology of 𝐾3 surfaces via mirror symmetry J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-06-09 Nick Sheridan; Ivan Smith
Abstract:We study the symplectic topology of certain surfaces (including the ``mirror quartic'' and ``mirror double plane''), equipped with certain Kähler forms. In particular, we prove that the symplectic Torelli group may be infinitely generated, and derive new constraints on Lagrangian tori. The key input, via homological mirror symmetry, is a result of Bayer and Bridgeland on the autoequivalence
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Combinatorial constructions of derived equivalences J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-05-05 Daniel Halpern-Leistner; Steven Sam
Abstract:Given a certain kind of linear representation of a reductive group, referred to as a quasi-symmetric representation in recent work of Špenko and Van den Bergh, we construct equivalences between the derived categories of coherent sheaves of its various geometric invariant theory (GIT) quotients for suitably generic stability parameters. These variations of GIT quotient are examples of more
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Zéro-cycles sur les espaces homogènes et problème de Galois inverse J. Am. Math. Soc. (IF 5.413) Pub Date : 2020-03-10 Yonatan Harpaz; Olivier Wittenberg
Abstract:Soit une compactification lisse d'un espace homogène d'un groupe algébrique linéaire sur un corps de nombres . Nous établissons la conjecture de Colliot-Thélène, Sansuc, Kato et Saito sur l'image du groupe de Chow des zéro-cycles de dans le produit des mêmes groupes sur tous les complétés de . Lorsque est semi-simple et simplement connexe et que le stabilisateur géométrique est fini et