Implemented code to compute pathwidth (= Node search number, vertex separation number, interval thickness) I am looking for an implementation of an algorithm to compute the pathwidth of a graph. It is well known that computing the pathwidth is equivalent to computing the node searching number, vertex separation number, or interval thickness of the graph. The algorithm does not have to be very fast; I want to run it on graphs of at most 20 vertices. I do require the algorithm to compute the pathwidth exactly, rather than giving an approximation.

I am aware that there are some implementations to compute the treewidth of a graph (a related concept) but have not been able to find any to compute the pathwidth. Any pointers are appreciated!
Don't know about "an implementation" but check out

Computing Pathwidth Faster Than 2^n 
Karol Suchan and Yngve Villanger 
Parameterized and Exact Computation, 4th International Workshop, IWPEC 2009,Copenhagen, Denmark, Springer Verlag, Lecture Notes in Computer Science 5917, Pages 324-335.