Automorphisms of Manifolds and Algebraic $K$-Theory: Part III

Automorphisms of Manifolds and Algebraic $K$-Theory: Part III PDF Author: Michael S. Weiss
Publisher: American Mathematical Soc.
ISBN: 147040981X
Category : Mathematics
Languages : en
Pages : 122

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Book Description
The structure space of a closed topological -manifold classifies bundles whose fibers are closed -manifolds equipped with a homotopy equivalence to . The authors construct a highly connected map from to a concoction of algebraic -theory and algebraic -theory spaces associated with . The construction refines the well-known surgery theoretic analysis of the block structure space of in terms of -theory.

Automorphisms of Manifolds and Algebraic $K$-Theory: Part III

Automorphisms of Manifolds and Algebraic $K$-Theory: Part III PDF Author: Michael S. Weiss
Publisher: American Mathematical Soc.
ISBN: 147040981X
Category : Mathematics
Languages : en
Pages : 122

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Book Description
The structure space of a closed topological -manifold classifies bundles whose fibers are closed -manifolds equipped with a homotopy equivalence to . The authors construct a highly connected map from to a concoction of algebraic -theory and algebraic -theory spaces associated with . The construction refines the well-known surgery theoretic analysis of the block structure space of in terms of -theory.

Sheaves on Graphs, Their Homological Invariants, and a Proof of the Hanna Neumann Conjecture

Sheaves on Graphs, Their Homological Invariants, and a Proof of the Hanna Neumann Conjecture PDF Author: Joel Friedman
Publisher: American Mathematical Soc.
ISBN: 1470409887
Category : Mathematics
Languages : en
Pages : 124

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Book Description
In this paper the author establishes some foundations regarding sheaves of vector spaces on graphs and their invariants, such as homology groups and their limits. He then uses these ideas to prove the Hanna Neumann Conjecture of the 1950s; in fact, he proves a strengthened form of the conjecture.

Quasi-Linear Perturbations of Hamiltonian Klein-Gordon Equations on Spheres

Quasi-Linear Perturbations of Hamiltonian Klein-Gordon Equations on Spheres PDF Author: J.-M. Delort
Publisher: American Mathematical Soc.
ISBN: 1470409836
Category : Mathematics
Languages : en
Pages : 92

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Book Description
The Hamiltonian ∫X(∣∂tu∣2+∣∇u∣2+m2∣u∣2)dx, defined on functions on R×X, where X is a compact manifold, has critical points which are solutions of the linear Klein-Gordon equation. The author considers perturbations of this Hamiltonian, given by polynomial expressions depending on first order derivatives of u. The associated PDE is then a quasi-linear Klein-Gordon equation. The author shows that, when X is the sphere, and when the mass parameter m is outside an exceptional subset of zero measure, smooth Cauchy data of small size ϵ give rise to almost global solutions, i.e. solutions defined on a time interval of length cNϵ−N for any N. Previous results were limited either to the semi-linear case (when the perturbation of the Hamiltonian depends only on u) or to the one dimensional problem. The proof is based on a quasi-linear version of the Birkhoff normal forms method, relying on convenient generalizations of para-differential calculus.

Shock Waves in Conservation Laws with Physical Viscosity

Shock Waves in Conservation Laws with Physical Viscosity PDF Author: Tai-Ping Liu
Publisher: American Mathematical Soc.
ISBN: 1470410168
Category : Mathematics
Languages : en
Pages : 180

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Book Description
The authors study the perturbation of a shock wave in conservation laws with physical viscosity. They obtain the detailed pointwise estimates of the solutions. In particular, they show that the solution converges to a translated shock profile. The strength of the perturbation and that of the shock are assumed to be small but independent. The authors' assumptions on the viscosity matrix are general so that their results apply to the Navier-Stokes equations for the compressible fluid and the full system of magnetohydrodynamics, including the cases of multiple eigenvalues in the transversal fields, as long as the shock is classical. The authors' analysis depends on accurate construction of an approximate Green's function. The form of the ansatz for the perturbation is carefully constructed and is sufficiently tight so that the author can close the nonlinear term through Duhamel's principle.

Julia Sets and Complex Singularities of Free Energies

Julia Sets and Complex Singularities of Free Energies PDF Author: Jianyong Qiao
Publisher: American Mathematical Soc.
ISBN: 1470409828
Category : Mathematics
Languages : en
Pages : 102

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Book Description
The author studies a family of renormalization transformations of generalized diamond hierarchical Potts models through complex dynamical systems. He proves that the Julia set (unstable set) of a renormalization transformation, when it is treated as a complex dynamical system, is the set of complex singularities of the free energy in statistical mechanics. He gives a sufficient and necessary condition for the Julia sets to be disconnected. Furthermore, he proves that all Fatou components (components of the stable sets) of this family of renormalization transformations are Jordan domains with at most one exception which is completely invariant. In view of the problem in physics about the distribution of these complex singularities, the author proves here a new type of distribution: the set of these complex singularities in the real temperature domain could contain an interval. Finally, the author studies the boundary behavior of the first derivative and second derivative of the free energy on the Fatou component containing the infinity. He also gives an explicit value of the second order critical exponent of the free energy for almost every boundary point.

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 PDF Author: Jochen Denzler
Publisher: American Mathematical Soc.
ISBN: 1470414082
Category : Mathematics
Languages : en
Pages : 94

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Book Description
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.

Analysis of the Hodge Laplacian on the Heisenberg Group

Analysis of the Hodge Laplacian on the Heisenberg Group PDF Author: Detlef Muller
Publisher: American Mathematical Soc.
ISBN: 1470409399
Category : Mathematics
Languages : en
Pages : 104

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Book Description
The authors consider the Hodge Laplacian \Delta on the Heisenberg group H_n, endowed with a left-invariant and U(n)-invariant Riemannian metric. For 0\le k\le 2n+1, let \Delta_k denote the Hodge Laplacian restricted to k-forms. In this paper they address three main, related questions: (1) whether the L^2 and L^p-Hodge decompositions, 1

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

Geometric Complexity Theory IV: Nonstandard Quantum Group for the Kronecker Problem PDF Author: Jonah Blasiak
Publisher: American Mathematical Soc.
ISBN: 1470410117
Category : Mathematics
Languages : en
Pages : 176

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Book Description
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.

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

Poincare-Einstein Holography for Forms via Conformal Geometry in the Bulk PDF Author: A. Rod Gover
Publisher: American Mathematical Soc.
ISBN: 1470410923
Category : Mathematics
Languages : en
Pages : 108

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Book Description
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.

Endoscopic Classification of Representations of Quasi-Split Unitary Groups

Endoscopic Classification of Representations of Quasi-Split Unitary Groups PDF Author: Chung Pang Mok
Publisher: American Mathematical Soc.
ISBN: 1470410419
Category : Mathematics
Languages : en
Pages : 260

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Book Description
In this paper the author establishes the endoscopic classification of tempered representations of quasi-split unitary groups over local fields, and the endoscopic classification of the discrete automorphic spectrum of quasi-split unitary groups over global number fields. The method is analogous to the work of Arthur on orthogonal and symplectic groups, based on the theory of endoscopy and the comparison of trace formulas on unitary groups and general linear groups.