Horizons of Fractal Geometry and Complex Dimensions

Horizons of Fractal Geometry and Complex Dimensions

Author: Robert G. Niemeyer

Publisher: American Mathematical Soc.

Published: 2019-06-26

Total Pages: 320

ISBN-13: 1470435810

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This volume contains the proceedings of the 2016 Summer School on Fractal Geometry and Complex Dimensions, in celebration of Michel L. Lapidus's 60th birthday, held from June 21–29, 2016, at California Polytechnic State University, San Luis Obispo, California. The theme of the contributions is fractals and dynamics and content is split into four parts, centered around the following themes: Dimension gaps and the mass transfer principle, fractal strings and complex dimensions, Laplacians on fractal domains and SDEs with fractal noise, and aperiodic order (Delone sets and tilings).


Needle Decompositions in Riemannian Geometry

Needle Decompositions in Riemannian Geometry

Author: Bo’az Klartag

Publisher: American Mathematical Soc.

Published: 2017-09-25

Total Pages: 90

ISBN-13: 1470425424

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The localization technique from convex geometry is generalized to the setting of Riemannian manifolds whose Ricci curvature is bounded from below. In a nutshell, the author's method is based on the following observation: When the Ricci curvature is non-negative, log-concave measures are obtained when conditioning the Riemannian volume measure with respect to a geodesic foliation that is orthogonal to the level sets of a Lipschitz function. The Monge mass transfer problem plays an important role in the author's analysis.


Nonsmooth Differential Geometry-An Approach Tailored for Spaces with Ricci Curvature Bounded from Below

Nonsmooth Differential Geometry-An Approach Tailored for Spaces with Ricci Curvature Bounded from Below

Author: Nicola Gigli

Publisher: American Mathematical Soc.

Published: 2018-02-23

Total Pages: 174

ISBN-13: 1470427656

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The author discusses in which sense general metric measure spaces possess a first order differential structure. Building on this, spaces with Ricci curvature bounded from below a second order calculus can be developed, permitting the author to define Hessian, covariant/exterior derivatives and Ricci curvature.


Maximal Cohen-Macaulay Modules Over Non-Isolated Surface Singularities and Matrix Problems

Maximal Cohen-Macaulay Modules Over Non-Isolated Surface Singularities and Matrix Problems

Author: Igor Burban

Publisher: American Mathematical Soc.

Published: 2017-07-13

Total Pages: 134

ISBN-13: 1470425378

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In this article the authors develop a new method to deal with maximal Cohen–Macaulay modules over non–isolated surface singularities. In particular, they give a negative answer on an old question of Schreyer about surface singularities with only countably many indecomposable maximal Cohen–Macaulay modules. Next, the authors prove that the degenerate cusp singularities have tame Cohen–Macaulay representation type. The authors' approach is illustrated on the case of k as well as several other rings. This study of maximal Cohen–Macaulay modules over non–isolated singularities leads to a new class of problems of linear algebra, which the authors call representations of decorated bunches of chains. They prove that these matrix problems have tame representation type and describe the underlying canonical forms.


Applications of Polyfold Theory I: The Polyfolds of Gromov-Witten Theory

Applications of Polyfold Theory I: The Polyfolds of Gromov-Witten Theory

Author: H. Hofer

Publisher: American Mathematical Soc.

Published: 2017-07-13

Total Pages: 230

ISBN-13: 1470422034

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In this paper the authors start with the construction of the symplectic field theory (SFT). As a general theory of symplectic invariants, SFT has been outlined in Introduction to symplectic field theory (2000), by Y. Eliashberg, A. Givental and H. Hofer who have predicted its formal properties. The actual construction of SFT is a hard analytical problem which will be overcome be means of the polyfold theory due to the present authors. The current paper addresses a significant amount of the arising issues and the general theory will be completed in part II of this paper. To illustrate the polyfold theory the authors use the results of the present paper to describe an alternative construction of the Gromov-Witten invariants for general compact symplectic manifolds.


Special Values of the Hypergeometric Series

Special Values of the Hypergeometric Series

Author: Akihito Ebisu

Publisher: American Mathematical Soc.

Published: 2017-07-13

Total Pages: 108

ISBN-13: 1470425335

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In this paper, the author presents a new method for finding identities for hypergeoemtric series, such as the (Gauss) hypergeometric series, the generalized hypergeometric series and the Appell-Lauricella hypergeometric series. Furthermore, using this method, the author gets identities for the hypergeometric series and shows that values of at some points can be expressed in terms of gamma functions, together with certain elementary functions. The author tabulates the values of that can be obtained with this method and finds that this set includes almost all previously known values and many previously unknown values.


Rationality Problem for Algebraic Tori

Rationality Problem for Algebraic Tori

Author: Akinari Hoshi

Publisher: American Mathematical Soc.

Published: 2017-07-13

Total Pages: 228

ISBN-13: 1470424096

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The authors give the complete stably rational classification of algebraic tori of dimensions and over a field . In particular, the stably rational classification of norm one tori whose Chevalley modules are of rank and is given. The authors show that there exist exactly (resp. , resp. ) stably rational (resp. not stably but retract rational, resp. not retract rational) algebraic tori of dimension , and there exist exactly (resp. , resp. ) stably rational (resp. not stably but retract rational, resp. not retract rational) algebraic tori of dimension . The authors make a procedure to compute a flabby resolution of a -lattice effectively by using the computer algebra system GAP. Some algorithms may determine whether the flabby class of a -lattice is invertible (resp. zero) or not. Using the algorithms, the suthors determine all the flabby and coflabby -lattices of rank up to and verify that they are stably permutation. The authors also show that the Krull-Schmidt theorem for -lattices holds when the rank , and fails when the rank is ...


On Sudakov's Type Decomposition of Transference Plans with Norm Costs

On Sudakov's Type Decomposition of Transference Plans with Norm Costs

Author: Stefano Bianchini

Publisher: American Mathematical Soc.

Published: 2018-02-23

Total Pages: 124

ISBN-13: 1470427664

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The authors consider the original strategy proposed by Sudakov for solving the Monge transportation problem with norm cost with , probability measures in and absolutely continuous w.r.t. . The key idea in this approach is to decompose (via disintegration of measures) the Kantorovich optimal transportation problem into a family of transportation problems in , where are disjoint regions such that the construction of an optimal map is simpler than in the original problem, and then to obtain by piecing together the maps . When the norm is strictly convex, the sets are a family of -dimensional segments determined by the Kantorovich potential called optimal rays, while the existence of the map is straightforward provided one can show that the disintegration of (and thus of ) on such segments is absolutely continuous w.r.t. the -dimensional Hausdorff measure. When the norm is not strictly convex, the main problems in this kind of approach are two: first, to identify a suitable family of regions on which the transport problem decomposes into simpler ones, and then to prove the existence of optimal maps. In this paper the authors show how these difficulties can be overcome, and that the original idea of Sudakov can be successfully implemented. The results yield a complete characterization of the Kantorovich optimal transportation problem, whose straightforward corollary is the solution of the Monge problem in each set and then in . The strategy is sufficiently powerful to be applied to other optimal transportation problems.