Department of Computer Science, Taipei Municipal University of Education, No. 1, Ai-Guo West Road, Taipei 10048, Taiwan
        Copyright © 2012 Yen Hung Chen. This is an open access article distributed under the   Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
        
     
Abstract
Let  be an undirected graph with a weight function and a cost
function on edges. The constrained minimum spanning tree problem is to find a
minimum cost spanning tree T in G such that the total weight in T is at most a given bound B. In this paper, we present two polynomial time approximation schemes (PTASs) for the constrained minimum spanning tree problem.