The connected_components function in the BGL returns the connected component information in a "ComponentMap," in which the value for node i is the number c[i] of the component containing that node. Is the sequence of component numbers "restricted growth" ? That is, can I assume that c[0] = 0 and for i > 0, c[i] <= 1 + max(c[0], ..., c[i-1])? It would appear that this would be true, as a consequence of the easiest way to use depth-first search to find the components. And a brief attempt to read the source code encourages me to believe it. But I may not have understood the source code. And I do not find it stated in the boost documentation, nor in /The Boost Graph Library/. Thanks in advance for clarification on this point. Christopher Henrich chenrich@monmouth.com mathinteract.com