Hi, I would like to use the r_c_shortest_paths algorithm. My constraint is that given pairs of vertices i, j (each i have a single mate j) must have a distance between them which is consistent with a given distribution. I am looking for the path which is most consistent with this distribution. Does anybody have any experience of formulating such a constraint in BGL? The second problem is that I am currently modelling the problem with an undirected graph. The edges could be viewed as bi-directional, but only due to the double stranded nature of DNA. Once I have started on a path I just choose the label which is consistent with the direction I am going, but the graph is essentially undirected, you can always go in either direction down an edge. Could an undirected graph be used with this algorithm or must I use a directed graph? I have tried to ask this question before, hopefully this time I have phrased it better - plus I am actually ready to code it now. As always, any advice gratefully received. Adam. -- Dr Adam Spargo High Performance Assembly Group email: aws@sanger.ac.uk Wellcome Trust Sanger Institute Tel: +44 (0)1223 834244 x7728 Hinxton, Cambridge CB10 1SA Fax: +44 (0)1223 494919 -- The Wellcome Trust Sanger Institute is operated by Genome Research Limited, a charity registered in England with number 1021457 and a company registered in England with number 2742969, whose registered office is 215 Euston Road, London, NW1 2BE.