Evaluation function - Definition and Overview

An evaluation function, also known as heuristic evaluation function or static evaluation function by game-playing programs to estimate the value or goodness of a position in the minimax algorithm. The evaluation function is typically designed to be fast and accuracy is not a concern (therefore heuristic); the function looks only at the current position and does not explore possible moves (therefore static).

One popular strategy for constructing evaluation functions is as a weighted sum of various factors that are thought to influence the value of a position. For instance, an evaluation function for chess might take the form

 c1 * material + c2 * mobility + c3 * king safety + c4 * center control + ...

See also

• Heuristic
• Computer chess
• Minimax algorithm

External references

• http://alumni.imsa.edu/~stendahl/comp/txt/gnuchess.txt - Heuristic function used by GNU Chess