Admissible heuristics
	n A heuristic h(n) is admissible if for every node n,    h(n) ≤ h*(n), where h*(n) is the true cost to reach the goal state from n. n An admissible heuristic never overestimates the cost to reach the goal, i.e., it is optimistic n Example: hSLD(n) (never overestimates the actual road distance) n Theorem: If h(n) is admissible, A* using TREE- SEARCH is optimal