Take the 2-minute tour ×  I have a square-based map. Only
horizontal and vertical movement is allowed (no diagonals).
Movement cost is always 1.  I'm implementing an A* algorithm on
that map, using the Manhattan distance as a distance heuristic.
Is this heuristic consistent? Can I can avoid checking g(node)
against nodes that are in the CLOSED set?  Edit: By consistent I
mean monotonic.  share|improve this question If your movement
cost is uniform across every tile, you could replace A* with
Jump Point Search –  Nick Caplinger Jun 26 '13 at 0:32 Hey,
that's nice! –  Emiliano Jun 27 '13 at 11:31 add comment  4
Answers  up vote 9 down vote accepted  To actually answer your
question: the manhatten distance is consistent when you're
constrained to moving vertically/horizonally along an unweighted
grid (this can be easily shown by the definition on wikipedia).
So yes, in your case you can avoid rechecking nodes in the
closed set.  However, once you allow diagonal or any-angle
movement, manhatten distance becomes n