Scattering theory for p-forms on manifolds with cylindrical ends has a direct interpretation in terms of cohomology. Using the Hodge isomorphism, the scattering matrix at low energy may be regarded as operator on the cohomology of the boundary. Its value at zero describes the image of the absolute cohomology in the cohomology of the boundary. We show that the so-called scattering length, the Ei...

A main contribution of this paper is the explicit construction of comparison morphisms between the standard bar resolution and Bardzell’s minimal resolution for truncated quiver algebras (TQA’s). As a direct application we describe explicitely the Yoneda product and derive several results on the structure of the cohomology ring of TQA’s. For instance, we show that the product of odd degree coho...

In this note, we investigate the cycle class map between the rational Chow groups and the arithmetic Deligne cohomology, introduced by Green-Griffiths and AsakuraSaito. We show nontriviality of the Chern classes of flat bundles in the arithmetic Deligne Cohomology in some cases and our proofs also indicate that generic flat bundles can be expected to have nontrivial classes. This provides examp...

We study limits of discrete series with infinitesimal character zero for Sp4: their n-cohomology and their contribution to “nonclassical” automorphic cohomology of the period domain for Hodge structures of mirror quintic type. As an application, we obtain the first generalization beyond SU(2, 1) of a result of [C1], showing that this cohomology can be reached by cup products of pairs of “classi...

Let M be a symplectic manifold, equipped with a Hamiltonian action of a torus T . We give an explicit formula for the rational cohomology ring of the symplectic quotient M//T in terms of the cohomology ring of M and fixed point data. Under some restrictions, our formulas apply to integral cohomology. In certain cases these methods enable us to show that the cohomology of the reduced space is to...

We use bordism theory to construct periodic cohomology theories, which we call elliptic cohomology, for which the cohomology of a point is a ring of modular functions. These are complex-oriented multiplicative cohomology theories, with formal groups associated to the universal elliptic genus studied by a number of authors ([CC, LS, O, W1, Z]). We are unable to find a geometric description for t...

Periodic cyclic homology group associated to a mixed complex was introduced by Goodwillie. In this talk, I will explain how to apply this construction to the symplectic cochain complex of a Liouville domain and obtain two periodic symplectic cohomology theories, which are called periodic symplectic cohomology and finitely supported periodic symplectic cohomology, respectively. The main result i...

A lot of good properties of étale cohomology only hold for torsion coefficients. We use “enlargement of categories” as developed in [BS] to define a cohomology theory that inherits the important properties of étale cohomology while allowing greater flexibility with the coefficients. In particular, choosing coefficients Z/P Z (for P an infinite prime and Z the enlargement of Z) gives a Weil coho...

We approach Mackenzie’s LA-groupoids from a supergeometric point of view by introducing Q-groupoids. A Q-groupoid is a groupoid object in the category of Q-manifolds, and there is a faithful functor from the category of LA-groupoids to the category of Q-groupoids. Using this approach, we associate to every LA-groupoid a double complex whose cohomology simultaneously generalizes Lie groupoid coh...

1 Equivariant Cohomology 1 1.1 Group cohomology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2 Equivariant cohomology of topological spaces . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Equivariant vector bundles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.4 Equivariant pushforward . . . . . . . . . . . . . . . . . . . . . . . ....