color the vertices of D such that each color class of D induces an acyclic subdigraph. Thus,
the chromatic number of a tournament T is the minimum number of transitive
subtournaments which cover the vertex set of T. We show in this note that tournaments are
significantly simpler than graphs with respect to coloring. Indeed, while undirected graphs
can be altogether “locally simple”(every neighborhood is a stable set) and have large …