The Wikipedia states that:

"An evaluation function, also known as a heuristic evaluation function or static evaluation function, is a function used by game-playing programs to estimate the value or goodness of a position in the minimax and related algorithms."


Q: Is "goodness" an actual term in use in this context, or should it more properly be something like "perceived optimality"?

I ask because, in Combinatorial Game Theory for instance, a lighthearted term such as "loopy" is preferred by some mathematicians (Demaine) over the more serious term "cyclic" (Fraenkel).

On a related note, is the use of "position" instead of "node" preferred here as an acknowledgement of the heuristic nature of Evaluation Functions? (My understanding is that "position", "node" and "game" may all be interchangeable in certain contexts.)


Yes, "goodness" is a common description of the value generated by an evaluation function. For example, "Artificial Intelligence" p. 77; "Knowledge-Free and Learning-Based Methods in Intelligent Game Playing" p. 15; "Tenth Scandinavian Conference on Artificial Intelligence" p. 125; and "Algorithms and Networking for Computer Games" p. 80.

The "position" is to the complete state of the game at some instant. A single position includes the locations of every piece on a game board at that instant, and also includes a few other bits of information -- who's turn it is; whether castling is still a legal option; etc.

I suspect that "the position" is a synecdoche, referring to the total state by a small part, the physical location (physical position) of some piece on the game board, based on earlier usage in military tactics of "positioning" troops relative to natural cover or relative to enemy troops.

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  • $\begingroup$ Welcome to AI and thanks for the answer (and all the links!) When you use position in this context, are you referring to an individual piece, or the gamestate, in the sense of the position of all the pieces? In M games, we're using position to refer to "coordinates + value" because it involves Sudoku squares in a partisan economic context. $\endgroup$ – DukeZhou Mar 9 '18 at 18:50
  • $\begingroup$ @DukeZhou: Yes, I use "position" to refer to the complete gamestate, not merely the physical position of one individual piece -- thank you for commenting. I edited in response to your comment to clarify and reduce ambiguity. $\endgroup$ – David Cary Mar 24 '18 at 16:23

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