A*: Properties of the Cost Estimate

• If h’(n) is exactly h(n) for all n, then the search immediately converges to the optimal solution.

• If h'(n)=0 for all n, the search is breadth-first.

• If h' never overestimates h, and goal states are “correctly identified” then the first goal node found will be optimal

• If h' sometimes overestimates h, then the goal node found may be sub-optimal.

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