Hi, I'm new to using the BGL, and have been working on a problem that uses a directed acyclic grid graph and subgraphs, and computes shortest paths. In my problem, the subgraphs are determined by paths from one end to the other. It is possible to determine in constant time whether a grid point or edge is within the graph, by looking at the paths bounding the subgraph. I started out using adjacency_list and filtered_graph to limit the graph, but this is not optimal because adjacency_list iterates over all vertices in the original graph to filter them. Ideally I'd like to use the indices from the master graph but be able to dynamically iterate over them according to the computations the code performs to limit the scope of the graphs. However, I'm not sure if anyone has done anything like this, and I'm a little frightened of trying to write my own graph class into the BGL structure. (I've never dealt with such heavily templated code before, and am even more confused than when looking at the STL!) Are there any pointers anyone can give me that would make it easier to construct such a class? Another option I'll throw out: Might it be simpler to hack one of the shortest paths algorithms to do a better job of restricting itself based on the dynamic subgraph filtering? I considered this (the code looks shorter and simpler), but it'd be cleaner to have a new graph class. Thanks to any who can help me. Also, I'm using VC++ 6 so all the problems with partial template specialization (which I don't even understand) apply to me. --Todd C. Gleason