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Faithfully Quadratic Rings

2015-10-27 Mathematics
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Release : 2015-10-27
Genre : Mathematics
Kind : eBook
Book Rating : 686/5 ( reviews)

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Book Synopsis Faithfully Quadratic Rings by : M. Dickmann

Download or read book Faithfully Quadratic Rings written by M. Dickmann. This book was released on 2015-10-27. Available in PDF, EPUB and Kindle. Book excerpt: In this monograph the authors extend the classical algebraic theory of quadratic forms over fields to diagonal quadratic forms with invertible entries over broad classes of commutative, unitary rings where is not a sum of squares and is invertible. They accomplish this by: (1) Extending the classical notion of matrix isometry of forms to a suitable notion of -isometry, where is a preorder of the given ring, , or . (2) Introducing in this context three axioms expressing simple properties of (value) representation of elements of the ring by quadratic forms, well-known to hold in the field case.

Relative Nonhomogeneous Koszul Duality

2022-02-10 Mathematics
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Release : 2022-02-10
Genre : Mathematics
Kind : eBook
Book Rating : 408/5 ( reviews)

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Book Synopsis Relative Nonhomogeneous Koszul Duality by : Leonid Positselski

Download or read book Relative Nonhomogeneous Koszul Duality written by Leonid Positselski. This book was released on 2022-02-10. Available in PDF, EPUB and Kindle. Book excerpt: This research monograph develops the theory of relative nonhomogeneous Koszul duality. Koszul duality is a fundamental phenomenon in homological algebra and related areas of mathematics, such as algebraic topology, algebraic geometry, and representation theory. Koszul duality is a popular subject of contemporary research. This book, written by one of the world's leading experts in the area, includes the homogeneous and nonhomogeneous quadratic duality theory over a nonsemisimple, noncommutative base ring, the Poincare–Birkhoff–Witt theorem generalized to this context, and triangulated equivalences between suitable exotic derived categories of modules, curved DG comodules, and curved DG contramodules. The thematic example, meaning the classical duality between the ring of differential operators and the de Rham DG algebra of differential forms, involves some of the most important objects of study in the contemporary algebraic and differential geometry. For the first time in the history of Koszul duality the derived D-\Omega duality is included into a general framework. Examples highly relevant for algebraic and differential geometry are discussed in detail.

Proof of the 1-Factorization and Hamilton Decomposition Conjectures

2016-10-05 Mathematics
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Release : 2016-10-05
Genre : Mathematics
Kind : eBook
Book Rating : 252/5 ( reviews)

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Book Synopsis Proof of the 1-Factorization and Hamilton Decomposition Conjectures by : Béla Csaba

Download or read book Proof of the 1-Factorization and Hamilton Decomposition Conjectures written by Béla Csaba. This book was released on 2016-10-05. Available in PDF, EPUB and Kindle. Book excerpt: In this paper the authors prove the following results (via a unified approach) for all sufficiently large n: (i) [1-factorization conjecture] Suppose that n is even and D≥2⌈n/4⌉−1. Then every D-regular graph G on n vertices has a decomposition into perfect matchings. Equivalently, χ′(G)=D. (ii) [Hamilton decomposition conjecture] Suppose that D≥⌊n/2⌋. Then every D-regular graph G on n vertices has a decomposition into Hamilton cycles and at most one perfect matching. (iii) [Optimal packings of Hamilton cycles] Suppose that G is a graph on n vertices with minimum degree δ≥n/2. Then G contains at least regeven(n,δ)/2≥(n−2)/8 edge-disjoint Hamilton cycles. Here regeven(n,δ) denotes the degree of the largest even-regular spanning subgraph one can guarantee in a graph on n vertices with minimum degree δ. (i) was first explicitly stated by Chetwynd and Hilton. (ii) and the special case δ=⌈n/2⌉ of (iii) answer questions of Nash-Williams from 1970. All of the above bounds are best possible.

The $abc$-Problem for Gabor Systems

2016-10-05 Mathematics
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Release : 2016-10-05
Genre : Mathematics
Kind : eBook
Book Rating : 155/5 ( reviews)

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Book Synopsis The $abc$-Problem for Gabor Systems by : Xin-Rong Dai

Download or read book The $abc$-Problem for Gabor Systems written by Xin-Rong Dai. This book was released on 2016-10-05. Available in PDF, EPUB and Kindle. Book excerpt: A longstanding problem in Gabor theory is to identify time-frequency shifting lattices aZ×bZ and ideal window functions χI on intervals I of length c such that {e−2πinbtχI(t−ma): (m,n)∈Z×Z} are Gabor frames for the space of all square-integrable functions on the real line. In this paper, the authors create a time-domain approach for Gabor frames, introduce novel techniques involving invariant sets of non-contractive and non-measure-preserving transformations on the line, and provide a complete answer to the above abc-problem for Gabor systems.

Monoidal Categories and the Gerstenhaber Bracket in Hochschild Cohomology

2016-09-06 Mathematics
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Release : 2016-09-06
Genre : Mathematics
Kind : eBook
Book Rating : 955/5 ( reviews)

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Book Synopsis Monoidal Categories and the Gerstenhaber Bracket in Hochschild Cohomology by : Reiner Hermann:

Download or read book Monoidal Categories and the Gerstenhaber Bracket in Hochschild Cohomology written by Reiner Hermann:. This book was released on 2016-09-06. Available in PDF, EPUB and Kindle. Book excerpt: In this monograph, the author extends S. Schwede's exact sequence interpretation of the Gerstenhaber bracket in Hochschild cohomology to certain exact and monoidal categories. Therefore the author establishes an explicit description of an isomorphism by A. Neeman and V. Retakh, which links Ext-groups with fundamental groups of categories of extensions and relies on expressing the fundamental group of a (small) category by means of the associated Quillen groupoid. As a main result, the author shows that his construction behaves well with respect to structure preserving functors between exact monoidal categories. The author uses his main result to conclude, that the graded Lie bracket in Hochschild cohomology is an invariant under Morita equivalence. For quasi-triangular bialgebras, he further determines a significant part of the Lie bracket's kernel, and thereby proves a conjecture by L. Menichi. Along the way, the author introduces n-extension closed and entirely extension closed subcategories of abelian categories, and studies some of their properties.

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