# Admissible heuristic

> In computer science, specifically in algorithms related to pathfinding, a heuristic function is said to be admissible if it never overestimates the cost of reaching the goal, i.e. the cost it estimates to reach the goal is not higher than the lowest possible cost from the current point in the path. In other words, it […]

In computer science, specifically in algorithms related to pathfinding, a heuristic function is said to be **admissible** if it never overestimates the cost of reaching the goal, i.e. the cost it estimates to reach the goal is not higher than the lowest possible cost from the current point in the path. In other words, it should act as a lower bound.

It is related to the concept of consistent heuristics. While all consistent heuristics are admissible, not all admissible heuristics are consistent.

## Search algorithms

An admissible heuristic is used to estimate the cost of reaching the goal state in an informed search algorithm. In order for a heuristic

to be admissible to the search problem, the estimated cost must always be lower than or equal to the actual cost of reaching the goal state.

The search algorithm uses the admissible heuristic to find an estimated

optimal path to the goal state from the current node.

For example, in A* search the evaluation function (where





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*Source: [Wikipedia](https://en.wikipedia.org/wiki/Admissible_heuristic)*

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- **URL:** https://wpsearchai.com/admissible-heuristic/
- **Published:** 2026-01-28T18:45:49+00:00
- **Modified:** 2026-01-28T18:45:49+00:00
- **Author:** admin
- **Categories:** Artificial intelligence