In [1] Johnson, Robertson, Seymour and Thomas define the notion of directed tree-width dtw(D) of a directed graph D. They ask whether dtw(D) ≥ k − 1 implies that D has a have...
We consider various well-known, equivalent complexity measures for graphs such as elimination orderings, k-trees and cops and robber games and study their natural translations to ...
Abstract. Although Cai, F¨urer and Immerman have shown that fixedpoint logic with counting (IFP + C) does not express all polynomialtime properties of finite structures, there h...
We propose a new parameter for the complexity of finite directed graphs which measures to what extent the cycles of the graph are intertwined. This measure, called entanglement, i...