It's no longer necessarily a minimum spanning tree. The exact algorithm will depend upon whether your starting set of edges always is a tree. Regards ... ____________________Reply Separator____________________ Subject: [Boost-users] graph: Min Spanning Tree (advanced start) Author: Matthew Galati Date: 12/11/2003 11:24 AM Is there a way to give an advanced start to solve Min Spanning Tree using boost/graph? That is, I have a list of edges in my graph that must be in the Min Spanning Tree (i.e., their cost is -M, for very big M). Since algorithms for MST are greedy, I assume this can be done - but is their an easy way to interface to boost/graph's MST algorithms?