Gorenstein Liaison Complete Intersection Liaison Invariants And Unobstructedness

Author : Jan Oddvar Kleppe,Juan C. Migliore,Rosa Miró-Roig
Publisher : American Mathematical Soc.
Page : 116 pages
File Size : 41,7 Mb
Release : 2001
Category : Mathematics
ISBN : 9780821827383

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Gorenstein Liaison, Complete Intersection Liaison Invariants and Unobstructedness by Jan Oddvar Kleppe,Juan C. Migliore,Rosa Miró-Roig Pdf

This paper contributes to the liaison and obstruction theory of subschemes in $\mathbb{P}^n$ having codimension at least three. The first part establishes several basic results on Gorenstein liaison. A classical result of Gaeta on liaison classes of projectively normal curves in $\mathbb{P}^3$ is generalized to the statement that every codimension $c$ ""standard determinantal scheme"" (i.e. a scheme defined by the maximal minors of a $t\times (t+c-1)$ homogeneous matrix), is in the Gorenstein liaison class of a complete intersection. Then Gorenstein liaison (G-liaison) theory is developed as a theory of generalized divisors on arithmetically Cohen-Macaulay schemes. In particular, a rather general construction of basic double G-linkage is introduced, which preserves the even G-liaison class.This construction extends the notion of basic double linkage, which plays a fundamental role in the codimension two situation. The second part of the paper studies groups which are invariant under complete intersection linkage, and gives a number of geometric applications of these invariants. Several differences between Gorenstein and complete intersection liaison are highlighted. For example, it turns out that linearly equivalent divisors on a smooth arithmetically Cohen-Macaulay subscheme belong, in general, to different complete intersection liaison classes, but they are always contained in the same even Gorenstein liaison class. The third part develops the interplay between liaison theory and obstruction theory and includes dimension estimates of various Hilbert schemes. For example, it is shown that most standard determinantal subschemes of codimension $3$ are unobstructed, and the dimensions of their components in the corresponding Hilbert schemes are computed.

Author : Maria Emilia Alonso,Enrique Arrondo,Raquel Mallavibarrena,Ignacio Sols
Publisher : Springer Science & Business Media
Page : 294 pages
File Size : 51,9 Mb
Release : 2011-01-30
Category : Mathematics
ISBN : 9783034602013

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Liaison, Schottky Problem and Invariant Theory by Maria Emilia Alonso,Enrique Arrondo,Raquel Mallavibarrena,Ignacio Sols Pdf

Federico Gaeta (1923–2007) was a Spanish algebraic geometer who was a student of Severi. He is considered to be one of the founders of linkage theory, on which he published several key papers. After many years abroad he came back to Spain in the 1980s. He spent his last period as a professor at Universidad Complutense de Madrid. In gratitude to him, some of his personal and mathematically close persons during this last station, all of whom bene?ted in one way or another by his ins- ration, have joined to edit this volume to keep his memory alive. We o?er in it surveys and original articles on the three main subjects of Gaeta’s interest through his mathematical life. The volume opens with a personal semblance by Ignacio Sols and a historical presentation by Ciro Ciliberto of Gaeta’s Italian period. Then it is divided into three parts, each of them devoted to a speci?c subject studied by Gaeta and coordinated by one of the editors. For each part, we had the advice of another colleague of Federico linked to that particular subject, who also contributed with a short survey. The ?rst part, coordinated by E. Arrondo with the advice of R.M.

Author : Markus Banagl
Publisher : American Mathematical Soc.
Page : 83 pages
File Size : 41,5 Mb
Release : 2002
Category : Mathematics
ISBN : 9780821829882

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Extending Intersection Homology Type Invariants to Non-Witt Spaces by Markus Banagl Pdf

Intersection homology theory provides a way to obtain generalized Poincare duality, as well as a signature and characteristic classes, for singular spaces. For this to work, one has had to assume however that the space satisfies the so-called Witt condition. We extend this approach to constructing invariants to spaces more general than Witt spaces. We present an algebraic framework for extending generalized Poincare duality and intersection homology to singular spaces $X$ not necessarily Witt. The initial step in this program is to define the category $SD(X)$ of complexes of sheaves suitable for studying intersection homology type invariants on non-Witt spaces. The objects in this category can be shown to be the closest possible self-dual 'approximation' to intersection homology sheaves.It is therefore desirable to understand the structure of such self-dual sheaves and to isolate the minimal data necessary to construct them. As the main tool in this analysis we introduce the notion of a Lagrangian structure (related to the familiar notion of Lagrangian submodules for $(-1)^k$-Hermitian forms, as in surgery theory). We demonstrate that every complex in $SD(X)$ has naturally associated Lagrangian structures and conversely, that Lagrangian structures serve as the natural building blocks for objects in $SD(X).Our main result asserts that there is in fact an equivalence of categories between $SD(X)$ and a twisted product of categories of Lagrangian structures. This may be viewed as a Postnikov system for $SD(X)$ whose fibers are categories of Lagrangian structures. The question arises as to which varieties possess Lagrangian structures. To begin to answer that, we define the model-class of varieties with an ordered resolution and use block bundles to describe the geometry of such spaces. Our main result concerning these is that they have associated preferred Lagrangian structures, and hence self-dual generalized intersection homology sheaves.

Author : Anonim
Publisher : Edicions Universitat Barcelona
Page : 138 pages
File Size : 48,8 Mb
Release : 2024-06-30
Category : Electronic
ISBN : 8210379456XXX

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Collectanea Mathematica by Anonim Pdf

Author : Geometry and Their Interactions International Conference on Midwest Algebra
Publisher : American Mathematical Soc.
Page : 270 pages
File Size : 43,5 Mb
Release : 2007
Category : Mathematics
ISBN : 9780821840948

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Algebra, Geometry and Their Interactions by Geometry and Their Interactions International Conference on Midwest Algebra Pdf

This volume's papers present work at the cutting edge of current research in algebraic geometry, commutative algebra, numerical analysis, and other related fields, with an emphasis on the breadth of these areas and the beneficial results obtained by the interactions between these fields. This collection of two survey articles and sixteen refereed research papers, written by experts in these fields, gives the reader a greater sense of some of the directions in which this research is moving, as well as a better idea of how these fields interact with each other and with other applied areas. The topics include blowup algebras, linkage theory, Hilbert functions, divisors, vector bundles, determinantal varieties, (square-free) monomial ideals, multiplicities and cohomological degrees, and computer vision.

Author : Desmond Sheiham
Publisher : American Mathematical Soc.
Page : 110 pages
File Size : 43,9 Mb
Release : 2003
Category : Mathematics
ISBN : 9780821833407

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Invariants of Boundary Link Cobordism by Desmond Sheiham Pdf

An $n$-dimensional $\mu$-component boundary link is a codimension $2$ embedding of spheres $L=\sqcup_{\mu}S^n \subset S^{n+2}$ such that there exist $\mu$ disjoint oriented embedded $(n+1)$-manifolds which span the components of $L$. An $F_\mu$-link is a boundary link together with a cobordism class of such spanning manifolds. The $F_\mu$-link cobordism group $C_n(F_\mu)$ is known to be trivial when $n$ is even but not finitely generated when $n$ is odd. Our main result is an algorithm to decide whether two odd-dimensional $F_\mu$-links represent the same cobordism class in $C_{2q-1}(F_\mu)$ assuming $q>1$. We proceed to compute the isomorphism class of $C_{2q-1}(F_\mu)$, generalizing Levine's computation of the knot cobordism group $C_{2q-1}(F_1)$.Our starting point is the algebraic formulation of Levine, Ko and Mio who identify $C_{2q-1}(F_\mu)$ with a surgery obstruction group, the Witt group $G^{(-1)^q,\mu}(\Z)$ of $\mu$-component Seifert matrices. We obtain a complete set of torsion-free invariants by passing from integer coefficients to complex coefficients and by applying the algebraic machinery of Quebbemann, Scharlau and Schulte. Signatures correspond to 'algebraically integral' simple self-dual representations of a certain quiver (directed graph with loops). These representations, in turn, correspond to algebraic integers on an infinite disjoint union of real affine varieties. To distinguish torsion classes, we consider rational coefficients in place of complex coefficients, expressing $G^{(-1)^q,\mu}(\mathbb{Q})$ as an infinite direct sum of Witt groups of finite-dimensional division $\mathbb{Q}$-algebras with involution.The Witt group of every such algebra appears as a summand infinitely often. The theory of symmetric and hermitian forms over these division algebras is well-developed. There are five classes of algebras to be considered; complete Witt invariants are available for four classes, those for which the local-global principle applies. An algebra in the fifth class, namely a quaternion algebra with non-standard involution, requires an additional Witt invariant which is defined if all the local invariants vanish.

Author : Pierre Lochak,J.-P. Marco,D. Sauzin
Publisher : American Mathematical Soc.
Page : 162 pages
File Size : 42,9 Mb
Release : 2003
Category : Hamiltonian systems
ISBN : 9780821832684

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On the Splitting of Invariant Manifolds in Multidimensional Near-Integrable Hamiltonian Systems by Pierre Lochak,J.-P. Marco,D. Sauzin Pdf

Presents the problem of the splitting of invariant manifolds in multidimensional Hamiltonian systems, stressing the canonical features of the problem. This book offers introduction of a canonically invariant scheme for the computation of the splitting matrix.

Author : Alan Forrest,John Hunton,Johannes Kellendonk
Publisher : American Mathematical Soc.
Page : 137 pages
File Size : 52,5 Mb
Release : 2002
Category : Aperiodic tilings
ISBN : 9780821829653

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Topological Invariants for Projection Method Patterns by Alan Forrest,John Hunton,Johannes Kellendonk Pdf

This memoir develops, discusses and compares a range of commutative and non-commutative invariants defined for projection method tilings and point patterns. The projection method refers to patterns, particularly the quasiperiodic patterns, constructed by the projection of a strip of a high dimensional integer lattice to a smaller dimensional Euclidean space. In the first half of the memoir the acceptance domain is very general - any compact set which is the closure of its interior - while in the second half the authors concentrate on the so-called canonical patterns. The topological invariants used are various forms of $K$-theory and cohomology applied to a variety of both $C DEGREES*$-algebras and dynamical systems derived from such a p

Author : José Ignacio Cogolludo-Agustín
Publisher : American Mathematical Soc.
Page : 97 pages
File Size : 42,9 Mb
Release : 2002
Category : Cohomology operations
ISBN : 9780821829424

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Topological Invariants of the Complement to Arrangements of Rational Plane Curves by José Ignacio Cogolludo-Agustín Pdf

The authors analyse two topological invariants of an embedding of an arrangement of rational plane curves in the projective complex plane, namely, the cohomology ring of the complement and the characteristic varieties. Their main result states that the cohomology ring of the complement to a rational arrangement is generated by logarithmic 1 and 2-forms and its structure depends on a finite number of invariants of the curve (its combinatorial type).

Author : Roger Chalkley
Publisher : American Mathematical Soc.
Page : 223 pages
File Size : 49,6 Mb
Release : 2002
Category : Differential equations, Linear
ISBN : 9780821827819

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Basic Global Relative Invariants for Homogeneous Linear Differential Equations by Roger Chalkley Pdf

Given any fixed integer $m \ge 3$, the author presents simple formulas for $m - 2$ algebraically independent polynomials over $\mathbb{Q}$ having the remarkable property, with respect to transformations of homogeneous linear differential equations of order $m$, that each polynomial is both a semi-invariant of the first kind (with respect to changes of the dependent variable) and a semi-invariant of the second kind (with respect to changes of the independent variable). These relative invariants are suitable for global studies in several different contexts and do not require Laguerre-Forsyth reductions for their evaluation. In contrast, all of the general formulas for basic relative invariants that have been proposed by other researchers during the last 113 years are merely local ones that are either much too complicated or require a Laguerre-Forsyth reduction for each evaluation.

Author : Nguyen Tu CUONG,Le Tuan HOA,Ngo Viet TRUNG
Publisher : Springer
Page : 258 pages
File Size : 55,8 Mb
Release : 2018-08-02
Category : Mathematics
ISBN : 9783319755656

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Commutative Algebra and its Interactions to Algebraic Geometry by Nguyen Tu CUONG,Le Tuan HOA,Ngo Viet TRUNG Pdf

This book presents four lectures on recent research in commutative algebra and its applications to algebraic geometry. Aimed at researchers and graduate students with an advanced background in algebra, these lectures were given during the Commutative Algebra program held at the Vietnam Institute of Advanced Study in Mathematics in the winter semester 2013 -2014. The first lecture is on Weyl algebras (certain rings of differential operators) and their D-modules, relating non-commutative and commutative algebra to algebraic geometry and analysis in a very appealing way. The second lecture concerns local systems, their homological origin, and applications to the classification of Artinian Gorenstein rings and the computation of their invariants. The third lecture is on the representation type of projective varieties and the classification of arithmetically Cohen -Macaulay bundles and Ulrich bundles. Related topics such as moduli spaces of sheaves, liaison theory, minimal resolutions, and Hilbert schemes of points are also covered. The last lecture addresses a classical problem: how many equations are needed to define an algebraic variety set-theoretically? It systematically covers (and improves) recent results for the case of toric varieties.

Author : Brendan Hassett,James McKernan,Jason Starr,Ravi Vakil
Publisher : American Mathematical Soc.
Page : 614 pages
File Size : 51,6 Mb
Release : 2013-09-11
Category : Mathematics
ISBN : 9780821889831

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A Celebration of Algebraic Geometry by Brendan Hassett,James McKernan,Jason Starr,Ravi Vakil Pdf

This volume resulted from the conference A Celebration of Algebraic Geometry, which was held at Harvard University from August 25-28, 2011, in honor of Joe Harris' 60th birthday. Harris is famous around the world for his lively textbooks and enthusiastic teaching, as well as for his seminal research contributions. The articles are written in this spirit: clear, original, engaging, enlivened by examples, and accessible to young mathematicians. The articles in this volume focus on the moduli space of curves and more general varieties, commutative algebra, invariant theory, enumerative geometry both classical and modern, rationally connected and Fano varieties, Hodge theory and abelian varieties, and Calabi-Yau and hyperkähler manifolds. Taken together, they present a comprehensive view of the long frontier of current knowledge in algebraic geometry. Titles in this series are co-published with the Clay Mathematics Institute (Cambridge, MA).

Author : Robert Ray Bruner,John Patrick Campbell Greenlees
Publisher : American Mathematical Soc.
Page : 144 pages
File Size : 55,7 Mb
Release : 2003
Category : Algebraic topology
ISBN : 9780821833667

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The Connective K-Theory of Finite Groups by Robert Ray Bruner,John Patrick Campbell Greenlees Pdf

Includes a paper that deals the connective K homology and cohomology of finite groups $G$. This title uses the methods of algebraic geometry to study the ring $ku DEGREES*(BG)$ where $ku$ denotes connective complex K-theory. It describes the variety in terms of the category of abelian $p$-subgroups of $G$ for primes $p$ dividing the group

Author : Michael Cwikel,Per G. Nilsson,Gideon Schechtman
Publisher : American Mathematical Soc.
Page : 127 pages
File Size : 44,6 Mb
Release : 2003
Category : Mathematics
ISBN : 9780821833827

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Interpolation of Weighted Banach Lattices/A Characterization of Relatively Decomposable Banach Lattices by Michael Cwikel,Per G. Nilsson,Gideon Schechtman Pdf

Interpolation of Weighted Banach Lattices It is known that for many, but not all, compatible couples of Banach spaces $(A_{0},A_{1})$ it is possible to characterize all interpolation spaces with respect to the couple via a simple monotonicity condition in terms of the Peetre $K$-functional. Such couples may be termed Calderon-Mityagin couples. The main results of the present paper provide necessary and sufficient conditions on a couple of Banach lattices of measurable functions $(X_{0},X_{1})$ which ensure that, for all weight functions $w_{0}$ and $w_{1}$, the couple of weighted lattices $(X_{0,w_{0}},X_{1,w_{1}})$ is a Calderon-Mityagin couple. Similarly, necessary and sufficient conditions are given for two couples of Banach lattices $(X_{0},X_{1})$ and $(Y_{0},Y_{1})$ to have the property that, for all choices of weight functions $w_{0}, w_{1}, v_{0}$ and $v_{1}$, all relative interpolation spaces with respect to the weighted couples $(X_{0,w_{0}},X_{1,w_{1}})$ and $(Y_{0,v_{0}},Y_{1,v_{1}})$ may be described via an obvious analogue of the above-mentioned $K$-functional monotonicity condition. A number of auxiliary results developed in the course of this work can also be expected to be useful in other contexts. These include a formula for the $K$-functional for an arbitrary couple of lattices which offers some of the features of Holmstedt's formula for $K(t,f;L^{p},L^{q})$, and also the following uniqueness theorem for Calderon's spaces $X^{1-\theta }_{0}X^{\theta }_{1}$: Suppose that the lattices $X_0$, $X_1$, $Y_0$ and $Y_1$ are all saturated and have the Fatou property. If $X^{1-\theta }_{0}X^{\theta }_{1} = Y^{1-\theta }_{0}Y^{\theta }_{1}$ for two distinct values of $\theta $ in $(0,1)$, then $X_{0} = Y_{0}$ and $X_{1} = Y_{1}$. Yet another such auxiliary result is a generalized version of Lozanovskii's formula $\left( X_{0}^{1-\theta }X_{1}^{\theta }\right) ^{\prime }=\left (X_{0}^{\prime }\right) ^{1-\theta }\left( X_{1}^{\prime }\right) ^{\theta }$ for the associate space of $X^{1-\theta }_{0}X^{\theta }_{1}$. A Characterization of Relatively Decomposable Banach Lattices Two Banach lattices of measurable functions $X$ and $Y$ are said to be relatively decomposable if there exists a constant $D$ such that whenever two functions $f$ and $g$ can be expressed as sums of sequences of disjointly supported elements of $X$ and $Y$ respectively, $f = \sum^{\infty }_{n=1} f_{n}$ and $g = \sum^{\infty }_{n=1} g_{n}$, such that $\ g_{n}\ _{Y} \le \ f_{n}\ _{X}$ for all $n = 1, 2, \ldots $, and it is given that $f \in X$, then it follows that $g \in Y$ and $\ g\ _{Y} \le D\ f\ _{X}$. Relatively decomposable lattices appear naturally in the theory of interpolation of weighted Banach lattices. It is shown that $X$ and $Y$ are relatively decomposable if and only if, for some $r \in [1,\infty ]$, $X$ satisfies a lower $r$-estimate and $Y$ satisfies an upper $r$-estimate. This is also equivalent to the condition that $X$ and $\ell ^{r}$ are relatively decomposable and also $\ell ^{r}$ and $Y$ are relatively decomposable.

Author : Arnd Scheel
Publisher : American Mathematical Soc.
Page : 86 pages
File Size : 54,6 Mb
Release : 2003
Category : Mathematics
ISBN : 9780821833735

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Radially Symmetric Patterns of Reaction-diffusion Systems by Arnd Scheel Pdf

In this paper, bifurcations of stationary and time-periodic solutions to reaction-diffusion systems are studied. We develop a center-manifold and normal form theory for radial dynamics which allows for a complete description of radially symmetric patterns. In particular, we show the existence of localized pulses near saddle-nodes, critical Gibbs kernels in the cusp, focus patterns in Turing instabilities, and active or passive target patterns in oscillatory instabilities.