Graph Theory on English AI Terms Dictionary

Lifelong Planning A*

Sat, 18 Jul 2026 10:04:58 +0000

Definition

Lifelong Planning A* (LPA*) is an extension of the A* search algorithm designed for environments where costs change over time. Instead of restarting the search, LPA* maintains a priority queue and updates only the affected nodes when edge weights are modified. This makes it highly efficient for robotics and navigation systems operating in partially known or changing terrains, significantly reducing computational overhead compared to standard replanning methods.

Summary

An incremental pathfinding algorithm that efficiently updates shortest paths in dynamic graphs without recomputing from scratch after edge weight changes.

And–or tree

Sat, 18 Jul 2026 09:45:36 +0000

Definition

An And–or tree is a representation used in problem-solving and planning, particularly in AI search algorithms. ‘Or’ nodes represent choices between different actions, while ‘And’ nodes indicate that all subsequent sub-nodes must be satisfied to achieve a goal. This structure helps decompose complex problems into manageable subproblems, facilitating efficient search strategies like AO* for finding optimal solutions in non-deterministic environments.

Summary

A hierarchical graph structure used in search algorithms where nodes represent states and edges represent actions leading to subgoals.

Admissible heuristic

Sat, 18 Jul 2026 09:44:54 +0000

Definition

In pathfinding and search problems, an admissible heuristic provides a lower bound on the actual cost to reach the target node. By guaranteeing that the estimated cost is always less than or equal to the real cost, algorithms like A* can ensure they find the shortest path if one exists. This property is critical for maintaining solution optimality while still leveraging heuristics to prune the search space efficiently, balancing speed and accuracy in complex graph traversals.