Hamilton decompositions and -factorizations of hypercubes.
Let be a fixed rooted digraph. The -coloring problem is the problem of deciding for which rooted digraphs there is a homomorphism which maps the vertex to the vertex . Let be a rooted oriented path. In this case we characterize the nonexistence of such a homomorphism by the existence of a rooted oriented cycle , which is homomorphic to but not homomorphic to . Such a property of the digraph is called rooted cycle duality or -cycle duality. This extends the analogical result for...