摘要

We show that if G is a graph with minimum degree at least three, then gamma(t)(G) <= alpha'(G) + (pc(G)-1)/2 and this bound is tight, where gamma(t)(G) is the total domination number of G, alpha'(G) the matching number of G and pc(G) the path covering number of G which is the minimum number of vertex disjoint paths such that every vertex belongs to a path in the cover. We show that if G is a connected graph on at least six vertices, then gamma(nt)(G) <= alpha'(G) + pc(G)/2 and this bound is tight, where gamma(nt)(G) denotes the neighborhood total domination number of G. We observe that every graph G of order n satisfies alpha'(G) + pc(G)/2 >= n/2, and we characterize the trees achieving equality in this bound.

  • 出版日期2017-1-6