A Power Law of Order 1/4 for Critical Mean Field Swendsen-Wang Dynamics

A Power Law of Order 1/4 for Critical Mean Field Swendsen-Wang Dynamics
Author: Yun Long
Publisher: American Mathematical Soc.
Total Pages: 96
Release: 2014-09-29
Genre: Mathematics
ISBN: 1470409100

Introduction Statement of the results Mixing time preliminaries Outline of the proof of Theorem 2.1 Random graph estimates Supercritical case Subcritical case Critical Case Fast mixing of the Swendsen-Wang process on trees Acknowledgements Bibliography

Brandt Matrices and Theta Series over Global Function Fields

Brandt Matrices and Theta Series over Global Function Fields
Author: Chih-Yun Chuang
Publisher: American Mathematical Soc.
Total Pages: 76
Release: 2015-08-21
Genre: Mathematics
ISBN: 1470414198

The aim of this article is to give a complete account of the Eichler-Brandt theory over function fields and the basis problem for Drinfeld type automorphic forms. Given arbitrary function field k together with a fixed place ∞, the authors construct a family of theta series from the norm forms of "definite" quaternion algebras, and establish an explicit Hecke-module homomorphism from the Picard group of an associated definite Shimura curve to a space of Drinfeld type automorphic forms. The "compatibility" of these homomorphisms with different square-free levels is also examined. These Hecke-equivariant maps lead to a nice description of the subspace generated by the authors' theta series, and thereby contributes to the so-called basis problem. Restricting the norm forms to pure quaternions, the authors obtain another family of theta series which are automorphic functions on the metaplectic group, and this results in a Shintani-type correspondence between Drinfeld type forms and metaplectic forms.

Higher-Order Time Asymptotics of Fast Diffusion in Euclidean Space: A Dynamical Systems Approach

Higher-Order Time Asymptotics of Fast Diffusion in Euclidean Space: A Dynamical Systems Approach
Author: Jochen Denzler
Publisher: American Mathematical Soc.
Total Pages: 94
Release: 2015-02-06
Genre: Mathematics
ISBN: 1470414082

This paper quantifies the speed of convergence and higher-order asymptotics of fast diffusion dynamics on Rn to the Barenblatt (self similar) solution. Degeneracies in the parabolicity of this equation are cured by re-expressing the dynamics on a manifold with a cylindrical end, called the cigar. The nonlinear evolution becomes differentiable in Hölder spaces on the cigar. The linearization of the dynamics is given by the Laplace-Beltrami operator plus a transport term (which can be suppressed by introducing appropriate weights into the function space norm), plus a finite-depth potential well with a universal profile. In the limiting case of the (linear) heat equation, the depth diverges, the number of eigenstates increases without bound, and the continuous spectrum recedes to infinity. The authors provide a detailed study of the linear and nonlinear problems in Hölder spaces on the cigar, including a sharp boundedness estimate for the semigroup, and use this as a tool to obtain sharp convergence results toward the Barenblatt solution, and higher order asymptotics. In finer convergence results (after modding out symmetries of the problem), a subtle interplay between convergence rates and tail behavior is revealed. The difficulties involved in choosing the right functional spaces in which to carry out the analysis can be interpreted as genuine features of the equation rather than mere annoying technicalities.

Critical Population and Error Threshold on the Sharp Peak Landscape for a Moran Model

Critical Population and Error Threshold on the Sharp Peak Landscape for a Moran Model
Author: Raphaël Cerf
Publisher: American Mathematical Soc.
Total Pages: 100
Release: 2014-12-20
Genre: Mathematics
ISBN: 1470409674

The goal of this work is to propose a finite population counterpart to Eigen's model, which incorporates stochastic effects. The author considers a Moran model describing the evolution of a population of size of chromosomes of length over an alphabet of cardinality . The mutation probability per locus is . He deals only with the sharp peak landscape: the replication rate is for the master sequence and for the other sequences. He studies the equilibrium distribution of the process in the regime where

Poincare-Einstein Holography for Forms via Conformal Geometry in the Bulk

Poincare-Einstein Holography for Forms via Conformal Geometry in the Bulk
Author: A. Rod Gover
Publisher: American Mathematical Soc.
Total Pages: 108
Release: 2015-04-09
Genre: Mathematics
ISBN: 1470410923

The authors study higher form Proca equations on Einstein manifolds with boundary data along conformal infinity. They solve these Laplace-type boundary problems formally, and to all orders, by constructing an operator which projects arbitrary forms to solutions. They also develop a product formula for solving these asymptotic problems in general. The central tools of their approach are (i) the conformal geometry of differential forms and the associated exterior tractor calculus, and (ii) a generalised notion of scale which encodes the connection between the underlying geometry and its boundary. The latter also controls the breaking of conformal invariance in a very strict way by coupling conformally invariant equations to the scale tractor associated with the generalised scale.

Geometric Complexity Theory IV: Nonstandard Quantum Group for the Kronecker Problem

Geometric Complexity Theory IV: Nonstandard Quantum Group for the Kronecker Problem
Author: Jonah Blasiak
Publisher: American Mathematical Soc.
Total Pages: 176
Release: 2015-04-09
Genre: Mathematics
ISBN: 1470410117

The Kronecker coefficient is the multiplicity of the -irreducible in the restriction of the -irreducible via the natural map , where are -vector spaces and . A fundamental open problem in algebraic combinatorics is to find a positive combinatorial formula for these coefficients. The authors construct two quantum objects for this problem, which they call the nonstandard quantum group and nonstandard Hecke algebra. They show that the nonstandard quantum group has a compact real form and its representations are completely reducible, that the nonstandard Hecke algebra is semisimple, and that they satisfy an analog of quantum Schur-Weyl duality.

On the Differential Structure of Metric Measure Spaces and Applications

On the Differential Structure of Metric Measure Spaces and Applications
Author: Nicola Gigli
Publisher: American Mathematical Soc.
Total Pages: 104
Release: 2015-06-26
Genre: Mathematics
ISBN: 1470414201

The main goals of this paper are: (i) To develop an abstract differential calculus on metric measure spaces by investigating the duality relations between differentials and gradients of Sobolev functions. This will be achieved without calling into play any sort of analysis in charts, our assumptions being: the metric space is complete and separable and the measure is Radon and non-negative. (ii) To employ these notions of calculus to provide, via integration by parts, a general definition of distributional Laplacian, thus giving a meaning to an expression like , where is a function and is a measure. (iii) To show that on spaces with Ricci curvature bounded from below and dimension bounded from above, the Laplacian of the distance function is always a measure and that this measure has the standard sharp comparison properties. This result requires an additional assumption on the space, which reduces to strict convexity of the norm in the case of smooth Finsler structures and is always satisfied on spaces with linear Laplacian, a situation which is analyzed in detail.

Deformation Quantization for Actions of Kahlerian Lie Groups

Deformation Quantization for Actions of Kahlerian Lie Groups
Author: Pierre Bieliavsky
Publisher: American Mathematical Soc.
Total Pages: 166
Release: 2015-06-26
Genre: Mathematics
ISBN: 1470414910

Let B be a Lie group admitting a left-invariant negatively curved Kählerian structure. Consider a strongly continuous action of B on a Fréchet algebra . Denote by the associated Fréchet algebra of smooth vectors for this action. In the Abelian case BR and isometric, Marc Rieffel proved that Weyl's operator symbol composition formula (the so called Moyal product) yields a deformation through Fréchet algebra structures R on . When is a -algebra, every deformed Fréchet algebra admits a compatible pre- -structure, hence yielding a deformation theory at the level of -algebras too. In this memoir, the authors prove both analogous statements for general negatively curved Kählerian groups. The construction relies on the one hand on combining a non-Abelian version of oscillatory integral on tempered Lie groups with geom,etrical objects coming from invariant WKB-quantization of solvable symplectic symmetric spaces, and, on the second hand, in establishing a non-Abelian version of the Calderón-Vaillancourt Theorem. In particular, the authors give an oscillating kernel formula for WKB-star products on symplectic symmetric spaces that fiber over an exponential Lie group.

Level One Algebraic Cusp Forms of Classical Groups of Small Rank

Level One Algebraic Cusp Forms of Classical Groups of Small Rank
Author: Gaëtan Chenevier
Publisher: American Mathematical Soc.
Total Pages: 134
Release: 2015-08-21
Genre: Mathematics
ISBN: 147041094X

The authors determine the number of level 1, polarized, algebraic regular, cuspidal automorphic representations of GLn over Q of any given infinitesimal character, for essentially all n≤8. For this, they compute the dimensions of spaces of level 1 automorphic forms for certain semisimple Z-forms of the compact groups SO7, SO8, SO9 (and G2) and determine Arthur's endoscopic partition of these spaces in all cases. They also give applications to the 121 even lattices of rank 25 and determinant 2 found by Borcherds, to level one self-dual automorphic representations of GLn with trivial infinitesimal character, and to vector valued Siegel modular forms of genus 3. A part of the authors' results are conditional to certain expected results in the theory of twisted endoscopy.