Title: Poincaredualitätsalgebren, Koinvarianten und Wu-Klassen
Abstract: Certain algebras of coinvariants have the extra structure of a Poincare duality algebra. We describe and characterize some of these Poincare duality algebras via Macaulay inverses of the ideal generated by the corresponding invariants. This can be helpful to decide some cases of the ideal membership problem.Another feature of Poincare duality algebras over finite fields is that they can be isomorphic to cohomology algebras of closed manifolds, so it makes sense to distinguish them by investigating if there Wu classes are trivial or not.We also try to find invariants in the coinvariants of the general linear group of a finite field. Finally we show that a general object introduced by J.F. Adams to prove some formulae about Wu classes and Steenrod operations is some kind of a ring of invariants.