Consistent heuristic and A* The following graph has consistent heuristic.


An A* algorithm will alter its first guess ACD to the correct shortest path ABD... if it has consistent heuristic, doesnt it mean, that AB should be found before AC?
A* isn't finished until all nodes with $f(n) &lt; f(goal)$ are expanded.

So even though you have added $D$ to the open set you still need to expand $B$ because $f(B) = 11 &lt; f(D) = 17$ after which $f(D)$ will become $12$