Noncommutative Tangent Cones and Calabi Yau Algebras

We study the generalization of the idea of a local quiver of a representation of a formally smooth algebra, to broader classes of finitely generated algebras. In this new setting we can construct for every semisimple representation M a local model and a noncommutative tangent cone. The representation schemes of these new algebras model the local structure and the tangent cone of the representation scheme of the original algebra at M . In this way one can try to classify algebras according to their local behavior. As an application we will show that the tangent cones of Calabi Yau 2 Algebras are always preprojective algebras. For Calabi Yau 3 Algebras the corresponding statement would be that the local model and the tangent cones derive from superpotentials. Although we do not have a proof in all cases, we will show that this will indeed hold in many cases.