$3$-Manifolds which Are End $1$-Movable

$3$-Manifolds which Are End $1$-Movable

Author: Matthew G. Brin

Publisher: American Mathematical Soc.

Published: 1989

Total Pages: 86

ISBN-13: 0821824740

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This paper continues a series by the authors on non-compact 3-manifolds. We describe the structure, up to end homeomorphism, of those orientable, non-compact 3-manifolds in which all loops near infinity [symbol] homotop to infinity [symbol] while staying near infinity [symbol] (the proper homotopy condition "end 1-movability" of the title). This extends previous work by others and by the authors because end 1-movability is weaker than properties studied before, and also because our result is the first to analyse a class of non-compact 3-manifolds whose defining properties include neither irreducibilty nor compact boundary. Our main tool is the end reduction--introduced in our earlier papers, developed further. End reductions are "simple" approximations of a non-compact 3-manifold that capture many of the manifold's properties.


Vertex Algebras and Integral Bases for the Enveloping Algebras of Affine Lie Algebras

Vertex Algebras and Integral Bases for the Enveloping Algebras of Affine Lie Algebras

Author: Shari A. Prevost

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 113

ISBN-13: 0821825275

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We present a new proof of the identities needed to exhibit an explicit [bold]Z-basis for the universal enveloping algebra associated to an affine Lie algebra. We then use the explicit [bold]Z-bases to extend Borcherds' description, via vertex operator representations, of a [bold]Z-form of the enveloping algebras for the simply-laced affine Lie algebras to the enveloping algebras associated to the unequal root length affine Lie algebras.


Sum of Even Powers of Real Linear Forms

Sum of Even Powers of Real Linear Forms

Author: Bruce Arie Reznick

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 169

ISBN-13: 0821825232

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This work initiates a systematic analysis of the representation of real forms of even degree as sums of powers of linear forms and the resulting implications in real algebraic geometry, number theory, combinatorics, functional analysis, and numerical analysis. The proofs utilize elementary techniques from linear algebra, convexity, number theory, and real algebraic geometry and many explicit examples and relevant historical remarks are presented.


Kernel Functions, Analytic Torsion, and Moduli Spaces

Kernel Functions, Analytic Torsion, and Moduli Spaces

Author: John David Fay

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 137

ISBN-13: 082182550X

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This memoir is a study of Ray-Singer analytic torsion for hermitian vector bundles on a compact Riemann surface [italic]C. The torsion is expressed through the trace of a modified resolvent. Thus, one can develop perturbation-curvature formulae for the Green-Szegö kernel and also for the torsion in terms of the Ahlfors-Bers complex structure of the Teichmuller space and Mumford complex structure of the moduli space of stable bundles of degree zero on [italic]C.


Neumann Systems for the Algebraic AKNS Problem

Neumann Systems for the Algebraic AKNS Problem

Author: Randolph James Schilling

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 79

ISBN-13: 0821825372

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This work is concerned with an algebraically completely integrable Hamiltonian system whose solutions may be used to describe the finite gap solutions of the AKNS spectral problem, a first order two-by-two matrix linear system. Trace formulas, constraints, Lax paris, and constants of motion are obtained using Krichever's algebraic inverse spectral transform. Computations are carried out explicityly over the class of spectral problems with square matrix coefficients.


Semistability of Amalgamated Products and HNN-Extensions

Semistability of Amalgamated Products and HNN-Extensions

Author: Michael L. Mihalik

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 98

ISBN-13: 0821825313

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In this work, the authors show that amalgamated products and HNN-extensions of finitely presented semistable at infinity groups are also semistable at infinity. A major step toward determining whether all finitely presented groups are semistable at infinity, this result easily generalizes to finite graphs of groups. The theory of group actions on trees and techniques derived from the proof of Dunwoody's accessibility theorem are key ingredients in this work.


Eigenvalues of the Laplacian for Hecke Triangle Groups

Eigenvalues of the Laplacian for Hecke Triangle Groups

Author: Dennis A. Hejhal

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 177

ISBN-13: 0821825291

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Paper I is concerned with computational aspects of the Selberg trace formalism, considering the usual type of eigenfunction and including an analysis of pseudo cusp forms and their residual effects. Paper II examines the modular group PSL (2, [bold]Z), as such groups have both a discrete and continuous spectrum. This paper only examines the discrete side of the spectrum.


Projective Modules over Lie Algebras of Cartan Type

Projective Modules over Lie Algebras of Cartan Type

Author: Daniel Ken Nakano

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 97

ISBN-13: 0821825305

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This paper investigates the question of linkage and block theory for Lie algebras of Cartan type. The second part of the paper deals mainly with block structure and projective modules of Lies algebras of types W and K.


A Generalization of Riemann Mappings and Geometric Structures on a Space of Domains in C$^n$

A Generalization of Riemann Mappings and Geometric Structures on a Space of Domains in C$^n$

Author: Stephen Semmes

Publisher: American Mathematical Soc.

Published: 1992

Total Pages: 111

ISBN-13: 0821825321

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Similar in philosophy to the study of moduli spaces in algebraic geometry, the central theme of this book is that spaces of (pseudoconvex) domains should admit geometrical structures that reflect the complex geometry of the underlying domains in a natural way. With its unusual geometric perspective of some topics in several complex variables, this book appeals to those who view much of mathematics in broadly geometrical terms.


Foliations and the Geometry of 3-Manifolds

Foliations and the Geometry of 3-Manifolds

Author: Danny Calegari

Publisher: Oxford University Press on Demand

Published: 2007-05-17

Total Pages: 378

ISBN-13: 0198570082

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This unique reference, aimed at research topologists, gives an exposition of the 'pseudo-Anosov' theory of foliations of 3-manifolds. This theory generalizes Thurston's theory of surface automorphisms and reveals an intimate connection between dynamics, geometry and topology in 3 dimensions. Significant themes returned to throughout the text include the importance of geometry, especially the hyperbolic geometry of surfaces, the importance of monotonicity, especially in1-dimensional and co-dimensional dynamics, and combinatorial approximation, using finite combinatorical objects such as train-tracks, branched surfaces and hierarchies to carry more complicated continuous objects.