Cohomology of Arithmetic Groups and Automorphic Forms Proceedings of a Conference held in Luminy/Marseille, France, May 22-27, 1989

Cohomology of arithmetic groups serves as a tool in studying possible relations between the theory of automorphic forms and the arithmetic of algebraic varieties resp. the geometry of locally symmetric spaces. These proceedings will serve as a guide to this still rapidly developing area of mathematics. Besides two survey articles, the contributions are original research papers.

Cohomology of arithmetic groups, automorphic forms and L-functions.- Limit multiplicities in L 2(??G).- Generalized modular symbols.- On Yoshida's theta lift.- Some results on the Eisenstein cohomology of arithmetic subgroups of GL n .- Period invariants of Hilbert modular forms, I: Trilinear differential operators and L-functions.- An effective finiteness theorem for ball lattices.- Unitary representations with nonzero multiplicities in L2(??G).- Signature des variétés modulaires de Hilbert et representations diédrales.- The Riemann-Hodge period relation for Hilbert modular forms of weight 2.- Modular symbols and the Steinberg representation.- Lefschetz numbers for arithmetic groups.- Boundary contributions to Lefschetz numbers for arithmetic groups I.- Embedding of Flensted-Jensen modules in L 2(??G) in the noncompact case.