Let G be a planar graph with n vertices whose vertex set is partitioned into subsets V0, . . . , Vk−1 for a positive integer 1 ≤ k ≤ n and let S be a set of n distinct points in the plane partitioned into subsets S0, . . . , Sk−1 with |Vi| = |Si| (0 ≤ i ≤ k − 1). This paper studies the problem of computing a crossing-free drawing of G such that each vertex of Vi is mapped to a distinct point of...

The homomorphisms of oriented or undirected graphs, the oriented chromatic number, the relationship between acyclic coloring number and oriented chromatic number, have been recently studied. Improving and combining earlier techniques of N. Alon and T. H. Marshall (1998, J. Algebraic Combin. 8, 5 13) and A. Raspaud and E. Sopena (1994, Inform. Process. Lett. 51, 171 174) we prove here a general ...

black forest horses are typically chestnut colored with flaxen mane and tail. however, as their coat color can get very dark, they are sometimes also indicated as silver, a color depending on a black base color. to analyse if the silver allele is present in the black forest horse population, we genotyped 250 horses of this breed for formerly reported coat color mutations within mc1r and silv. a...