If it's not an admissible heuristic, is it a consistent heuristic?
I am solving a problem in which, according to the given values, the heuristic is not admissible. According to my calculation from other similar problems, it should be consistent, as well as keeping in mind the values, but the solution says it's not consistent either. Can someone tell why?
For a heuristic to be admissible, it must never overestimate the distance from a state to the nearest goal state.
For a heuristic to be consistent, the heuristic's value must be less than or equal to the cost of moving from that state to the state nearest the goal that can be reached from it, plus the heurstic's estimate for that state.
What this means is that, as you move along the sequence of nodes from start to goal that the heuristic recommends, a consistent heuristic should monotonically decrease in value. A consistent heuristic is thus also always admissible.
Notice that this means that if a heuristic is not admissible (like yours), it is also not consistent (by the contrapositive).
Therefore, if you already know your heuristic is not admissible, you should not be surprised that it is not consistent.
It seems most likely that you may have confused the definition of consistent for monotone. A consistent heuristic is both monotone and admissible.
As Neil Says, if you want to know why your specific heuristic is inadmissible, you should post another question about it, or modify this one.