Hi Robert, >For example, if I could store a graph in a sqlite database, I'd like >to query the database to know if the graph contains a Eulerian >path[1].
I may be driven by a misleading uneducated impression, but given the nature of most graph-related algorithms --I see the search for Eulerian path as an exception-- I'd be surprised if SQL would prove superior to a decent application-level implementation. I don't mean it can't be done with SQL[ite], but the cost of access to vertice/edges data seems very high to me, compared to, say, a C implementation using a classical data structure. If your actual problem is exactly what you state above, then you can indeed determine if a graph is Eulerian by storing or computing the degree of each vertex. I believe it can be done simply with a trigger at the time you insert an edge. Then querying for Eulerian circuit property is equivalent to looking for "no odd degree within vertices" and Eulerian path is "only two vertices (start and end) have an odd degree". If you store your graph in SQLite only for that query, then I would question the usefulness of SQLite compared to a more classical solution. It all depends on the "life" of your vertices/edges/graphs. _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
