In the back of my mind, I seem to recall that path-finding A * algorithms like these actually aren't quite A * . IIRC, this is a constrained version of A * und

In the back of my mind, I seem to recall that path-finding A * algorithms like these actually aren't quite A * . IIRC, this is a constrained version of A * under the assumption that the heuristic h() is not only admissible but also monotonic, whereas A * only requires admissibility. The additional monotonicity constraint guarantees that the g() values of previously visited nodes never change, right? Otherwise if you find a better g() path you may have to do a lot of costly book-keeping. I presume the book-keeping is not part of the algorithm on display here.