1,567 research outputs found
Reflexivity and rigidity for complexes, II: Schemes
We prove basic facts about reflexivity in derived categories over noetherian
schemes; and about related notions such as semidualizing complexes, invertible
complexes, and Gorenstein-perfect maps. Also, we study a notion of rigidity
with respect to semidualizing complexes, in particular, relative dualizing
complexes for Gorenstein-perfect maps. Our results include theorems of
Yekutieli and Zhang concerning rigid dualizing complexes on schemes. This work
is a continuation of part I, which dealt with commutative rings.Comment: 40 page
Mechanisms with evidence: commitment and robustness
We show that in a class of Iāagent mechanism design problems with evidence, commitment is unnecessary, randomization has no value, and robust incentive compatibility has no cost. In particular, for each agent i, we construct a simple disclosure game between the principal and agent i where the equilibrium strategies of the agents in these disclosure games give their equilibrium strategies in the game corresponding to the mechanism but where the principal is not committed to his response. In this equilibrium, the principal obtains the same payoff as in the optimal mechanism with commitment. As an application, we show that certain costly verification models can be characterized using equilibrium analysis of an associated model of evidence.Accepted manuscrip
Reduction of derived Hochschild functors over commutative algebras and schemes
We study functors underlying derived Hochschild cohomology, also called
Shukla cohomology, of a commutative algebra S essentially of finite type and of
finite flat dimension over a commutative noetherian ring K. We construct a
complex of S-modules D, and natural reduction isomorphisms
Ext^*_{S\otimes^L_{K}S}(S|K;M\otimes^L_{K}N) ~ Ext^*_S(RHom_S(M,D),N) for all
complexes of S-modules N and all complexes M of finite flat dimension over K
whose homology H(M) is finitely generated over S; such isomorphisms determine D
up to derived isomorphism. Using Grothendieck duality theory we establish
analogous isomorphisms for any essentially finite type flat maps f: X->Y of
noetherian schemes, with f^!(O_Y) in place of D.Comment: 32 pages. Minor changes from previous version. To appear in the
Advances in Mathematic
Report of a Network Coordinating Group on Forages: Ad hoc Meeting, 21-22 April 2005, Lindau, Switzerland
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