... and w with the same color. Now the vertex v between u, w on P 4 is not in C, but since u, w areatdistanceatleast3onC the path uvw together with one of the u, w-segments of C yields a shorter non-contractible ... preliminaries Suppose F is a nonempty family of connected bipartite graphs, each with at least 3 vertices. An r-coloring of a graph G is said to be F-free if G contains no 2-...
Ngày tải lên: 07/08/2014, 08:20