What is admissible function?

An admissible function, often used in the context of search algorithms, is a heuristic that never overestimates the cost of reaching the goal from a given state. In other Words, it provides an optimistic estimate of the cost to reach the goal, ensuring that the function is always less than or equal to the actual cost. This property is crucial for algorithms like A* to guarantee optimality, as it helps guide the search process effectively while ensuring that the best solution is found.