Gromov, Cauchy and Causal Boundaries for Riemannian, Finslerian and Lorentzian Manifolds

Gromov, Cauchy and Causal Boundaries for Riemannian, Finslerian and Lorentzian Manifolds

Author: Jose Luis Flores

Publisher: American Mathematical Soc.

Published: 2013-10-23

Total Pages: 88

ISBN-13: 0821887750

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Recently, the old notion of causal boundary for a spacetime V has been redefined consistently. The computation of this boundary ∂V on any standard conformally stationary spacetime V=R×M, suggests a natural compactification MB associated to any Riemannian metric on M or, more generally, to any Finslerian one. The corresponding boundary ∂BM is constructed in terms of Busemann-type functions. Roughly, ∂BM represents the set of all the directions in M including both, asymptotic and "finite" (or "incomplete") directions. This Busemann boundary ∂BM is related to two classical boundaries: the Cauchy boundary ∂CM and the Gromov boundary ∂GM. The authors' aims are: (1) to study the subtleties of both, the Cauchy boundary for any generalized (possibly non-symmetric) distance and the Gromov compactification for any (possibly incomplete) Finsler manifold, (2) to introduce the new Busemann compactification MB, relating it with the previous two completions, and (3) to give a full description of the causal boundary ∂V of any standard conformally stationary spacetime. J. L. Flores and J. Herrera, University of Malaga, Spain, and M. Sánchez, University of Granada, Spain. Publisher's note.


Quantum Field Theory and Gravity

Quantum Field Theory and Gravity

Author: Felix Finster

Publisher: Springer Science & Business Media

Published: 2012-02-08

Total Pages: 389

ISBN-13: 3034800436

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One of the most challenging problems of contemporary theoretical physics is the mathematically rigorous construction of a theory which describes gravitation and the other fundamental physical interactions within a common framework. The physical ideas which grew from attempts to develop such a theory require highly advanced mathematical methods and radically new physical concepts. This book presents different approaches to a rigorous unified description of quantum fields and gravity. It contains a carefully selected cross-section of lively discussions which took place in autumn 2010 at the fifth conference "Quantum field theory and gravity - Conceptual and mathematical advances in the search for a unified framework" in Regensburg, Germany. In the tradition of the other proceedings covering this series of conferences, a special feature of this book is the exposition of a wide variety of approaches, with the intention to facilitate a comparison. The book is mainly addressed to mathematicians and physicists who are interested in fundamental questions of mathematical physics. It allows the reader to obtain a broad and up-to-date overview of a fascinating active research area.


Developments in Lorentzian Geometry

Developments in Lorentzian Geometry

Author: Alma L. Albujer

Publisher: Springer Nature

Published: 2022-10-06

Total Pages: 323

ISBN-13: 3031053796

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This proceedings volume gathers selected, revised papers presented at the X International Meeting on Lorentzian Geometry (GeLoCor 2021), virtually held at the University of Córdoba, Spain, on February 1-5, 2021. It includes surveys describing the state-of-the-art in specific areas, and a selection of the most relevant results presented at the conference. Taken together, the papers offer an invaluable introduction to key topics discussed at the conference and an overview of the main techniques in use today. This volume also gathers extended revisions of key studies in this field. Bringing new results and examples, these unique contributions offer new perspectives to the original problems and, in most cases, extend and reinforce the robustness of previous findings. Hosted every two years since 2001, the International Meeting on Lorentzian Geometry has become one of the main events bringing together the leading experts on Lorentzian geometry. In this volume, the reader will find studies on spatial and null hypersurfaces, low regularity in general relativity, conformal structures, Lorentz-Finsler spacetimes, and more. Given its scope, the book will be of interest to both young and experienced mathematicians and physicists whose research involves general relativity and semi-Riemannian geometry.


Advances in Lorentzian Geometry

Advances in Lorentzian Geometry

Author: Matthias Plaue

Publisher: American Mathematical Soc.

Published: 2011

Total Pages: 154

ISBN-13: 082185352X

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Offers insight into the methods and concepts of a very active field of mathematics that has many connections with physics. It includes contributions from specialists in differential geometry and mathematical physics, collectively demonstrating the wide range of applications of Lorentzian geometry, and ranging in character from research papers to surveys to the development of new ideas.


Nonlinear Stability of Ekman Boundary Layers in Rotating Stratified Fluids

Nonlinear Stability of Ekman Boundary Layers in Rotating Stratified Fluids

Author: Hajime Koba

Publisher: American Mathematical Soc.

Published: 2014-03-05

Total Pages: 142

ISBN-13: 0821891332

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A stationary solution of the rotating Navier-Stokes equations with a boundary condition is called an Ekman boundary layer. This book constructs stationary solutions of the rotating Navier-Stokes-Boussinesq equations with stratification effects in the case when the rotating axis is not necessarily perpendicular to the horizon. The author calls such stationary solutions Ekman layers. This book shows the existence of a weak solution to an Ekman perturbed system, which satisfies the strong energy inequality. Moreover, the author discusses the uniqueness of weak solutions and computes the decay rate of weak solutions with respect to time under some assumptions on the Ekman layers and the physical parameters. The author also shows that there exists a unique global-in-time strong solution of the perturbed system when the initial datum is sufficiently small. Comparing a weak solution satisfying the strong energy inequality with the strong solution implies that the weak solution is smooth with respect to time when time is sufficiently large.


Lorentzian Geometry and Related Topics

Lorentzian Geometry and Related Topics

Author: María A. Cañadas-Pinedo

Publisher: Springer

Published: 2018-03-06

Total Pages: 278

ISBN-13: 3319662902

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This volume contains a collection of research papers and useful surveys by experts in the field which provide a representative picture of the current status of this fascinating area. Based on contributions from the VIII International Meeting on Lorentzian Geometry, held at the University of Málaga, Spain, this volume covers topics such as distinguished (maximal, trapped, null, spacelike, constant mean curvature, umbilical...) submanifolds, causal completion of spacetimes, stationary regions and horizons in spacetimes, solitons in semi-Riemannian manifolds, relation between Lorentzian and Finslerian geometries and the oscillator spacetime. In the last decades Lorentzian geometry has experienced a significant impulse, which has transformed it from just a mathematical tool for general relativity to a consolidated branch of differential geometry, interesting in and of itself. Nowadays, this field provides a framework where many different mathematical techniques arise with applications to multiple parts of mathematics and physics. This book is addressed to differential geometers, mathematical physicists and relativists, and graduate students interested in the field.


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

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

Author: Michael S. Weiss

Publisher: American Mathematical Soc.

Published: 2014-08-12

Total Pages: 122

ISBN-13: 147040981X

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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.


Recent Trends in Lorentzian Geometry

Recent Trends in Lorentzian Geometry

Author: Miguel Sánchez

Publisher: Springer Science & Business Media

Published: 2012-11-06

Total Pages: 357

ISBN-13: 1461448972

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Traditionally, Lorentzian geometry has been used as a necessary tool to understand general relativity, as well as to explore new genuine geometric behaviors, far from classical Riemannian techniques. Recent progress has attracted a renewed interest in this theory for many researchers: long-standing global open problems have been solved, outstanding Lorentzian spaces and groups have been classified, new applications to mathematical relativity and high energy physics have been found, and further connections with other geometries have been developed. Samples of these fresh trends are presented in this volume, based on contributions from the VI International Meeting on Lorentzian Geometry, held at the University of Granada, Spain, in September, 2011. Topics such as geodesics, maximal, trapped and constant mean curvature submanifolds, classifications of manifolds with relevant symmetries, relations between Lorentzian and Finslerian geometries, and applications to mathematical physics are included. ​ This book will be suitable for a broad audience of differential geometers, mathematical physicists and relativists, and researchers in the field.


Transfer of Siegel Cusp Forms of Degree 2

Transfer of Siegel Cusp Forms of Degree 2

Author: Ameya Pitale

Publisher: American Mathematical Soc.

Published: 2014-09-29

Total Pages: 120

ISBN-13: 0821898566

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Let be the automorphic representation of generated by a full level cuspidal Siegel eigenform that is not a Saito-Kurokawa lift, and be an arbitrary cuspidal, automorphic representation of . Using Furusawa's integral representation for combined with a pullback formula involving the unitary group , the authors prove that the -functions are "nice". The converse theorem of Cogdell and Piatetski-Shapiro then implies that such representations have a functorial lifting to a cuspidal representation of . Combined with the exterior-square lifting of Kim, this also leads to a functorial lifting of to a cuspidal representation of . As an application, the authors obtain analytic properties of various -functions related to full level Siegel cusp forms. They also obtain special value results for and


Polynomial Approximation on Polytopes

Polynomial Approximation on Polytopes

Author: Vilmos Totik

Publisher: American Mathematical Soc.

Published: 2014-09-29

Total Pages: 124

ISBN-13: 1470416662

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Polynomial approximation on convex polytopes in is considered in uniform and -norms. For an appropriate modulus of smoothness matching direct and converse estimates are proven. In the -case so called strong direct and converse results are also verified. The equivalence of the moduli of smoothness with an appropriate -functional follows as a consequence. The results solve a problem that was left open since the mid 1980s when some of the present findings were established for special, so-called simple polytopes.