Incidence Theorems on manifolds by JŸrgen_Richter-Gebert The talk focuses on the interplay of geometric incidence theorems, algebraic structures and cycle structures on manifolds. It will we shown how the combinatorics of many proofs for incidence theorems can be considered as directly related to a cycle structure on triangulated manifolds. This relation, which interprets algebraic cancellation patterns in a topological way, can be used on the one hand to analyze incidence theorems in order to find an easy proof of the theorem. On the other hand it can be used to generate incidence theorems in a systematic way. Relations to oriented matroid theory and and the theory of polygonal tilings will be outlined during the talk.