International audienceWe study the following Constrained Bipartite Edge Coloring (CBEC) problem: We are given a bipartite graph G(U,V,E) of maximum degree l with n vertices, in which some of the edges have been legally colored with c colors. We wish to complete the coloring of the edges of G minimizing the total number of colors used. The problem has been proved to be NP-hard event for bipartite graphs of maximum degree three
