Hi, I was just trying to work up an example for a class I'm teaching, to illustrate implicit graphs. The following shows how far I've gotten: https://gist.github.com/4153918 This is attempting to apply Warnsdorff's heuristic (choose the next move with the least out-degree) using A* search. I'm running into several problems having to do with the requirements of astar_search_no_init. In particular, the requirement that we can assign an index to every vertex is quite painful, since enumerating all the possible vertices in the search space is difficult. Any advice here? I suppose I could keep a real map and simply assign indices in the order vertices are encountered, but that seems pretty ugly to me. Any hints? -- Dave Abrahams BoostPro Computing Software Development Training http://www.boostpro.com Clang/LLVM/EDG Compilers C++ Boost