An admissible heuristic never overestimates the cost of reaching a goal from a state. In A* search, this optimism helps prioritize promising routes without claiming that a remaining path is cheaper than it can actually be. section 14.5.1
Use the condition with these related checks:
- Pair admissibility with consistency when applying A* to general graphs: admissibility avoids overestimating a complete path, while consistency avoids overestimating an individual edge. section 14.5.1
- For trees, admissibility alone is sufficient because a node has only one path from the root to any goal through it. section 14.5.1
- Use straight-line distance to a delivery address as an optimistic guide: it favors paths moving toward the goal and can reduce visited vertices. section 14.5.1
