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Algebraic Properties Of Ext-Modules Over Complete Intersections, Jason Hardin
Algebraic Properties Of Ext-Modules Over Complete Intersections, Jason Hardin
Department of Mathematics: Dissertations, Theses, and Student Research
We investigate two algebraic properties of Ext-modules over a complete intersection R of codimension c. Given an R-module M, Ext(M,k) can be viewed as a graded module over a polynomial ring in c variables with an action given by the Eisenbud operators. We provide an upper bound on the degrees of the generators of this graded module in terms of the regularities of two associated coherent sheaves. In the codimension two case, our bound recovers a bound of Avramov and Buchweitz in terms of the Betti numbers of M. We also provide a description of the differential graded (DG) R-module …
Vanishing Of Ext And Tor Over Complete Intersections, Olgur Celikbas
Vanishing Of Ext And Tor Over Complete Intersections, Olgur Celikbas
Department of Mathematics: Dissertations, Theses, and Student Research
Let (R,m) be a local complete intersection, that is, a local ring whose m-adic completion is the quotient of a complete regular local ring by a regular sequence. Let M and N be finitely generated R-modules. This dissertation concerns the vanishing of Tor(M, N) and Ext(M, N). In this context, M satisfies Serre's condition (S_{n}) if and only if M is an nth syzygy. The complexity of M is the least nonnegative integer r such that the nth Betti number of M is bounded by a polynomial of degree r-1 for all sufficiently large n. We use this notion of …