On multi-Rees algebras. With an Appenddix by Ngô Viêt Trung.
Partial intersection subschemes of Pr of codimension c were used to furnish various graded Betti numbers which agree with a fixed Hilbert function. Here we study some further properties of such schemes; in particular, we show that they are not in general licci and we give a large class of them which are licci. Moreover, we show that all partial intersections are glicci. We also show that for partial intersections the first and the last Betti numbers, say m and p respectively, give bounds each other;...
Let , , be ideals of a Noetherian local ring . Let and be finitely generated -modules. We give a generalized version of the Duality Theorem for Cohen-Macaulay rings using local cohomology defined by a pair of ideals. We study the behavior of the endomorphism rings of and , where is the smallest integer such that the local cohomology with respect to a pair of ideals is nonzero and is the Matlis dual functor. We show that if is a -dimensional complete Cohen-Macaulay ring and ...
In this paper, we will present several necessary and sufficient conditions on a commutative ring such that the algebraic and geometric local cohomologies are equivalent.