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.

Published: 2014-12-20

Total Pages: 104

ISBN-13: 1470409399

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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 Aspects of Harmonic Analysis

Geometric Aspects of Harmonic Analysis PDF

Author: Paolo Ciatti

Publisher: Springer Nature

Published: 2021-09-27

Total Pages: 488

ISBN-13: 3030720586

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This volume originated in talks given in Cortona at the conference "Geometric aspects of harmonic analysis" held in honor of the 70th birthday of Fulvio Ricci. It presents timely syntheses of several major fields of mathematics as well as original research articles contributed by some of the finest mathematicians working in these areas. The subjects dealt with are topics of current interest in closely interrelated areas of Fourier analysis, singular integral operators, oscillatory integral operators, partial differential equations, multilinear harmonic analysis, and several complex variables. The work is addressed to researchers in the field.

Algebras of Singular Integral Operators with Kernels Controlled by Multiple Norms

Algebras of Singular Integral Operators with Kernels Controlled by Multiple Norms PDF

Author: Alexander Nagel

Publisher: American Mathematical Soc.

Published: 2019-01-08

Total Pages: 141

ISBN-13: 1470434385

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The authors study algebras of singular integral operators on R and nilpotent Lie groups that arise when considering the composition of Calderón-Zygmund operators with different homogeneities, such as operators occuring in sub-elliptic problems and those arising in elliptic problems. These algebras are characterized in a number of different but equivalent ways: in terms of kernel estimates and cancellation conditions, in terms of estimates of the symbol, and in terms of decompositions into dyadic sums of dilates of bump functions. The resulting operators are pseudo-local and bounded on for . . While the usual class of Calderón-Zygmund operators is invariant under a one-parameter family of dilations, the operators studied here fall outside this class, and reflect a multi-parameter structure.

Deformation Quantization for Actions of Kahlerian Lie Groups

Deformation Quantization for Actions of Kahlerian Lie Groups PDF

Author: Pierre Bieliavsky

Publisher: American Mathematical Soc.

Published: 2015-06-26

Total Pages: 166

ISBN-13: 1470414910

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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.

Irreducible Almost Simple Subgroups of Classical Algebraic Groups

Irreducible Almost Simple Subgroups of Classical Algebraic Groups PDF

Author: Timothy C. Burness

Publisher: American Mathematical Soc.

Published: 2015-06-26

Total Pages: 122

ISBN-13: 147041046X

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Let be a simple classical algebraic group over an algebraically closed field of characteristic with natural module . Let be a closed subgroup of and let be a nontrivial -restricted irreducible tensor indecomposable rational -module such that the restriction of to is irreducible. In this paper the authors classify the triples of this form, where and is a disconnected almost simple positive-dimensional closed subgroup of acting irreducibly on . Moreover, by combining this result with earlier work, they complete the classification of the irreducible triples where is a simple algebraic group over , and is a maximal closed subgroup of positive dimension.

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.

Published: 2015-04-09

Total Pages: 176

ISBN-13: 1470410117

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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.

Level One Algebraic Cusp Forms of Classical Groups of Small Rank

Level One Algebraic Cusp Forms of Classical Groups of Small Rank PDF

Author: Gaëtan Chenevier

Publisher: American Mathematical Soc.

Published: 2015-08-21

Total Pages: 134

ISBN-13: 147041094X

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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.

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.

Published: 2015-04-09

Total Pages: 260

ISBN-13: 1470410419

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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.

On the Differential Structure of Metric Measure Spaces and Applications

On the Differential Structure of Metric Measure Spaces and Applications PDF

Author: Nicola Gigli

Publisher: American Mathematical Soc.

Published: 2015-06-26

Total Pages: 104

ISBN-13: 1470414201

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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.