We survey results and open questions on complexity of parameterized problems on digraphs. The problems include the feedback vertex and arc set problems, induced subdigraph problem...
This paper gives an overview of results of the project "Beyond Timed Automata" carried out in the Collaborative Research Center AVACS (Automatic Verification and Analysi...
Let (x, y) be a bivariate polynomial with complex coefficients. The zeroes of (x, y) are given a combinatorial structure by considering them as arcs of a directed graph G(). This p...
The Positive-Negative Partial Set Cover problem is introduced and its complexity, especially the hardness-of-approximation, is studied. The problem generalizes the Set Cover probl...
Natural Dowling analogues of the complex of phylogenetic trees are studied. Using discrete Morse theory, we find their homotopy types. In the process, the homotopy types of certai...