On coloring problems for the two-season multigraphs

It is supposed that there are two moments of time called seasons in which a multigraph can have various sets of edges. Such multigraphs are called two-season. In coloring vertices or edges every object is colored in one season. Some bounds on two-season chromatic number are given and the exact algorithm for the minimal edge coloring of a bipartite two-season multigraph is presented. Bibliogr. 3.