Distribution of Resonances in Scattering by Thin Barriers

Distribution of Resonances in Scattering by Thin Barriers

Author: Jeffrey Galkowski

Publisher: American Mathematical Soc.

Published: 2019-06-10

Total Pages: 168

ISBN-13: 1470435721

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The author studies high energy resonances for the operators where is strictly convex with smooth boundary, may depend on frequency, and is the surface measure on .


A Local Relative Trace Formula for the Ginzburg-Rallis Model: The Geometric Side

A Local Relative Trace Formula for the Ginzburg-Rallis Model: The Geometric Side

Author: Chen Wan

Publisher: American Mathematical Soc.

Published: 2019-12-02

Total Pages: 102

ISBN-13: 1470436868

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Following the method developed by Waldspurger and Beuzart-Plessis in their proofs of the local Gan-Gross-Prasad conjecture, the author is able to prove the geometric side of a local relative trace formula for the Ginzburg-Rallis model. Then by applying such formula, the author proves a multiplicity formula of the Ginzburg-Rallis model for the supercuspidal representations. Using that multiplicity formula, the author proves the multiplicity one theorem for the Ginzburg-Rallis model over Vogan packets in the supercuspidal case.


New Complex Analytic Methods in the Study of Non-Orientable Minimal Surfaces in Rn

New Complex Analytic Methods in the Study of Non-Orientable Minimal Surfaces in Rn

Author: Antonio Alarcón

Publisher: American Mathematical Soc.

Published: 2020-05-13

Total Pages: 90

ISBN-13: 1470441616

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All the new tools mentioned above apply to non-orientable minimal surfaces endowed with a fixed choice of a conformal structure. This enables the authors to obtain significant new applications to the global theory of non-orientable minimal surfaces. In particular, they construct proper non-orientable conformal minimal surfaces in Rn with any given conformal structure, complete non-orientable minimal surfaces in Rn with arbitrary conformal type whose generalized Gauss map is nondegenerate and omits n hyperplanes of CPn−1 in general position, complete non-orientable minimal surfaces bounded by Jordan curves, and complete proper non-orientable minimal surfaces normalized by bordered surfaces in p-convex domains of Rn.


Nonlinear Diffusion Equations and Curvature Conditions in Metric Measure Spaces

Nonlinear Diffusion Equations and Curvature Conditions in Metric Measure Spaces

Author: Luigi Ambrosio

Publisher: American Mathematical Soc.

Published: 2020-02-13

Total Pages: 134

ISBN-13: 1470439131

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The aim of this paper is to provide new characterizations of the curvature dimension condition in the context of metric measure spaces (X,d,m). On the geometric side, the authors' new approach takes into account suitable weighted action functionals which provide the natural modulus of K-convexity when one investigates the convexity properties of N-dimensional entropies. On the side of diffusion semigroups and evolution variational inequalities, the authors' new approach uses the nonlinear diffusion semigroup induced by the N-dimensional entropy, in place of the heat flow. Under suitable assumptions (most notably the quadraticity of Cheeger's energy relative to the metric measure structure) both approaches are shown to be equivalent to the strong CD∗(K,N) condition of Bacher-Sturm.


Higher Orbifolds and Deligne-Mumford Stacks as Structured Infinity-Topoi

Higher Orbifolds and Deligne-Mumford Stacks as Structured Infinity-Topoi

Author: David Carchedi

Publisher: American Mathematical Soc.

Published: 2020

Total Pages: 132

ISBN-13: 1470441446

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The author develops a universal framework to study smooth higher orbifolds on the one hand and higher Deligne-Mumford stacks (as well as their derived and spectral variants) on the other, and use this framework to obtain a completely categorical description of which stacks arise as the functor of points of such objects. He chooses to model higher orbifolds and Deligne-Mumford stacks as infinity-topoi equipped with a structure sheaf, thus naturally generalizing the work of Lurie, but his approach applies not only to different settings of algebraic geometry such as classical algebraic geometry, derived algebraic geometry, and the algebraic geometry of commutative ring spectra but also to differential topology, complex geometry, the theory of supermanifolds, derived manifolds etc., where it produces a theory of higher generalized orbifolds appropriate for these settings. This universal framework yields new insights into the general theory of Deligne-Mumford stacks and orbifolds, including a representability criterion which gives a categorical characterization of such generalized Deligne-Mumford stacks. This specializes to a new categorical description of classical Deligne-Mumford stacks, which extends to derived and spectral Deligne-Mumford stacks as well.


Compact Quotients of Cahen-Wallach Spaces

Compact Quotients of Cahen-Wallach Spaces

Author: Ines Kath

Publisher: American Mathematical Soc.

Published: 2020-02-13

Total Pages: 96

ISBN-13: 1470441039

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Indecomposable symmetric Lorentzian manifolds of non-constant curvature are called Cahen-Wallach spaces. Their isometry classes are described by continuous families of real parameters. The authors derive necessary and sufficient conditions for the existence of compact quotients of Cahen-Wallach spaces in terms of these parameters.


Moufang Loops and Groups with Triality are Essentially the Same Thing

Moufang Loops and Groups with Triality are Essentially the Same Thing

Author: J. I. Hall

Publisher: American Mathematical Soc.

Published: 2019-09-05

Total Pages: 206

ISBN-13: 1470436221

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In 1925 Élie Cartan introduced the principal of triality specifically for the Lie groups of type D4, and in 1935 Ruth Moufang initiated the study of Moufang loops. The observation of the title in 1978 was made by Stephen Doro, who was in turn motivated by the work of George Glauberman from 1968. Here the author makes the statement precise in a categorical context. In fact the most obvious categories of Moufang loops and groups with triality are not equivalent, hence the need for the word “essentially.”


A Unified Approach to Structural Limits and Limits of Graphs with Bounded Tree-Depth

A Unified Approach to Structural Limits and Limits of Graphs with Bounded Tree-Depth

Author: Jaroslav Nešetřil

Publisher: American Mathematical Soc.

Published: 2020-04-03

Total Pages: 120

ISBN-13: 1470440652

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In this paper the authors introduce a general framework for the study of limits of relational structures and graphs in particular, which is based on a combination of model theory and (functional) analysis. The authors show how the various approaches to graph limits fit to this framework and that the authors naturally appear as “tractable cases” of a general theory. As an outcome of this, the authors provide extensions of known results. The authors believe that this puts these into a broader context. The second part of the paper is devoted to the study of sparse structures. First, the authors consider limits of structures with bounded diameter connected components and prove that in this case the convergence can be “almost” studied component-wise. They also propose the structure of limit objects for convergent sequences of sparse structures. Eventually, they consider the specific case of limits of colored rooted trees with bounded height and of graphs with bounded tree-depth, motivated by their role as “elementary bricks” these graphs play in decompositions of sparse graphs, and give an explicit construction of a limit object in this case. This limit object is a graph built on a standard probability space with the property that every first-order definable set of tuples is measurable. This is an example of the general concept of modeling the authors introduce here. Their example is also the first “intermediate class” with explicitly defined limit structures where the inverse problem has been solved.