Algebras whose Euler form is non-negative
Algebras with hypercritical Tits form
An isomorphism problem for algebras defined by some quivers and nonadmissible ideals
Given a quiver Q, a field K and two (not necessarily admissible) ideals I, I' in the path algebra KQ, we study the problem when the factor algebras KQ/I and KQ/I' of KQ are isomorphic. Sufficient conditions are given in case Q is a tree extension of a cycle.
An orbit closure for a representation of the Kronecker quiver with bad singularities
We give an example of a representation of the Kronecker quiver for which the closure of the corresponding orbit contains a singularity smoothly equivalent to the isolated singularity of two planes crossing at a point. Therefore this orbit closure is neither Cohen-Macaulay nor unibranch.
Auslander-Reiten triangles in derived categories.