IDA* (Iterative Deepening A*)

Depth-first with f-limit. Increase limit iteratively. O(depth) memory instead of O(states).

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ARA* (Anytime Repairing A*)

Start with inflated heuristic → suboptimal fast solution. Repeatedly reduce inflation → improve solution.

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D* Lite

Dynamic environments. When edges change, don't restart — incrementally update from goal backward.

Landmark-based A* (ALT)

Precompute distances to landmark nodes. Use triangle inequality as tight lower bound.