Generalized Descriptive Set Theory and Classification Theory

Generalized Descriptive Set Theory and Classification Theory PDF Author: Sy D. Friedman
Publisher:
ISBN: 9781470416713
Category : MATHEMATICS
Languages : en
Pages : 92

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Book Description
Descriptive set theory is mainly concerned with studying subsets of the space of all countable binary sequences. In this paper the authors study the generalization where countable is replaced by uncountable. They explore properties of generalized Baire and Cantor spaces equivalence relations and their Borel reducibility. The study shows that the descriptive set theory looks very different in this generalized setting compared to the classical countable case. They also draw the connection between the stability theoretic complexity of first-order theories and the descriptive set theoretic complexity of their isomorphism relations. The authors' results suggest that Borel reducibility on uncountable structures is a model theoretically natural way to compare the complexity of isomorphism relations.

Generalized Descriptive Set Theory and Classification Theory

Generalized Descriptive Set Theory and Classification Theory PDF Author: Sy D. Friedman
Publisher:
ISBN: 9781470416713
Category : MATHEMATICS
Languages : en
Pages : 92

Get Book

Book Description
Descriptive set theory is mainly concerned with studying subsets of the space of all countable binary sequences. In this paper the authors study the generalization where countable is replaced by uncountable. They explore properties of generalized Baire and Cantor spaces equivalence relations and their Borel reducibility. The study shows that the descriptive set theory looks very different in this generalized setting compared to the classical countable case. They also draw the connection between the stability theoretic complexity of first-order theories and the descriptive set theoretic complexity of their isomorphism relations. The authors' results suggest that Borel reducibility on uncountable structures is a model theoretically natural way to compare the complexity of isomorphism relations.

Generalized Descriptive Set Theory and Classification Theory

Generalized Descriptive Set Theory and Classification Theory PDF Author: Sy-David Friedman
Publisher: American Mathematical Soc.
ISBN: 0821894757
Category : Mathematics
Languages : en
Pages : 80

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Book Description
Descriptive set theory is mainly concerned with studying subsets of the space of all countable binary sequences. In this paper the authors study the generalization where countable is replaced by uncountable. They explore properties of generalized Baire and Cantor spaces, equivalence relations and their Borel reducibility. The study shows that the descriptive set theory looks very different in this generalized setting compared to the classical, countable case. They also draw the connection between the stability theoretic complexity of first-order theories and the descriptive set theoretic complexity of their isomorphism relations. The authors' results suggest that Borel reducibility on uncountable structures is a model theoretically natural way to compare the complexity of isomorphism relations.

Souslin Quasi-Orders and Bi-Embeddability of Uncountable Structures

Souslin Quasi-Orders and Bi-Embeddability of Uncountable Structures PDF Author: Alessandro Andretta
Publisher: American Mathematical Society
ISBN: 1470452731
Category : Mathematics
Languages : en
Pages : 189

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Book Description
View the abstract.

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.
ISBN: 1470410419
Category : Mathematics
Languages : en
Pages : 248

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Book Description
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.

Towards a General Theory of Classifications

Towards a General Theory of Classifications PDF Author: Daniel Parrochia
Publisher: Springer Science & Business Media
ISBN: 3034806094
Category : Mathematics
Languages : en
Pages : 322

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Book Description
This book is an essay on the epistemology of classifications. Its main purpose is not to provide an exposition of an actual mathematical theory of classifications, that is, a general theory which would be available to any kind of them: hierarchical or non-hierarchical, ordinary or fuzzy, overlapping or non-overlapping, finite or infinite, and so on, establishing a basis for all possible divisions of the real world. For the moment, such a theory remains nothing but a dream. Instead, the authors essentially put forward a number of key questions. Their aim is rather to reveal the “state of art” of this dynamic field and the philosophy one may eventually adopt to go further. To this end they present some advances made in the course of the last century, discuss a few tricky problems that remain to be solved, and show the avenues open to those who no longer wish to stay on the wrong track. Researchers and professionals interested in the epistemology and philosophy of science, library science, logic and set theory, order theory or cluster analysis will find this book a comprehensive, original and progressive introduction to the main questions in this field.

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.
ISBN: 1470410117
Category : Mathematics
Languages : en
Pages : 160

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Book Description
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.

Julia Sets and Complex Singularities of Free Energies

Julia Sets and Complex Singularities of Free Energies PDF Author: Jianyong Qiao
Publisher: American Mathematical Soc.
ISBN: 1470409828
Category : Mathematics
Languages : en
Pages : 89

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Book Description
The author studies a family of renormalization transformations of generalized diamond hierarchical Potts models through complex dynamical systems. He proves that the Julia set (unstable set) of a renormalization transformation, when it is treated as a complex dynamical system, is the set of complex singularities of the free energy in statistical mechanics. He gives a sufficient and necessary condition for the Julia sets to be disconnected. Furthermore, he proves that all Fatou components (components of the stable sets) of this family of renormalization transformations are Jordan domains with at most one exception which is completely invariant. In view of the problem in physics about the distribution of these complex singularities, the author proves here a new type of distribution: the set of these complex singularities in the real temperature domain could contain an interval. Finally, the author studies the boundary behavior of the first derivative and second derivative of the free energy on the Fatou component containing the infinity. He also gives an explicit value of the second order critical exponent of the free energy for almost every boundary point.

Index Theory for Locally Compact Noncommutative Geometries

Index Theory for Locally Compact Noncommutative Geometries PDF Author: A. L. Carey
Publisher: American Mathematical Soc.
ISBN: 0821898388
Category : Mathematics
Languages : en
Pages : 130

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Book Description
Spectral triples for nonunital algebras model locally compact spaces in noncommutative geometry. In the present text, the authors prove the local index formula for spectral triples over nonunital algebras, without the assumption of local units in our algebra. This formula has been successfully used to calculate index pairings in numerous noncommutative examples. The absence of any other effective method of investigating index problems in geometries that are genuinely noncommutative, particularly in the nonunital situation, was a primary motivation for this study and the authors illustrate this point with two examples in the text. In order to understand what is new in their approach in the commutative setting the authors prove an analogue of the Gromov-Lawson relative index formula (for Dirac type operators) for even dimensional manifolds with bounded geometry, without invoking compact supports. For odd dimensional manifolds their index formula appears to be completely new.

Automorphisms of Manifolds and Algebraic K-Theory: Part III

Automorphisms of Manifolds and Algebraic K-Theory: Part III PDF Author: Michael S. Weiss
Publisher: American Mathematical Soc.
ISBN: 147040981X
Category : Mathematics
Languages : en
Pages : 110

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Book Description
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.

A Geometric Theory for Hypergraph Matching

A Geometric Theory for Hypergraph Matching PDF Author: Peter Keevash
Publisher: American Mathematical Soc.
ISBN: 1470409658
Category : Mathematics
Languages : en
Pages : 95

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Book Description
The authors develop a theory for the existence of perfect matchings in hypergraphs under quite general conditions. Informally speaking, the obstructions to perfect matchings are geometric, and are of two distinct types: `space barriers' from convex geometry, and `divisibility barriers' from arithmetic lattice-based constructions. To formulate precise results, they introduce the setting of simplicial complexes with minimum degree sequences, which is a generalisation of the usual minimum degree condition. They determine the essentially best possible minimum degree sequence for finding an almost perfect matching. Furthermore, their main result establishes the stability property: under the same degree assumption, if there is no perfect matching then there must be a space or divisibility barrier. This allows the use of the stability method in proving exact results. Besides recovering previous results, the authors apply our theory to the solution of two open problems on hypergraph packings: the minimum degree threshold for packing tetrahedra in -graphs, and Fischer's conjecture on a multipartite form of the Hajnal-Szemerédi Theorem. Here they prove the exact result for tetrahedra and the asymptotic result for Fischer's conjecture; since the exact result for the latter is technical they defer it to a subsequent paper.