AbstractSiegel modular forms generalize the usual elliptic modular forms and show up in many parts of mathematics: algebraic geometry, number theory and even in mathematical physics. But they are difficult to construct. We show that invariant theory enables us to efficiently construct all (vector valued) Siegel modular forms of degree two and three from from certain basic modular forms provided...
Abstract:The topological group of homeomorphisms of d-dimensional Euclidean space is a basic object in geometric topology, closely related to understanding the difference between diffeomorphisms and homeomorphisms of all d-dimensional manifolds (except when d=4). I will explain some methods that have been used for studying the algebraic topology of this group, and report on a recently obtained...