Insofar as I understand, it appears that, before moving, all strong chess software
- examines thousands or millions of possible, future positions;
- evaluates each future position according to some heuristic, called an evaluation function;
- separately evaluates each future position for quiescence, to decide whether to explore continuations from the position;
- chooses from among available moves by minimax; and
- uses an opening book.
So far, so good. However, the strength of a chess program seems mostly to depend on the quality of its evaluation and quiescence heuristics -- and also on its opening book which, from the computer's perspective, is yet another heuristic. Such a chess program apparently, only, exactly knows as much about the game as does the human who has crafted the heuristics. The program seems to have no insights of its own.
Has anyone ever written a chess program that does have insights of its own? That learns the game on its own? That trains itself? Such a program would be provided with the rules of the game, of course, and would presumably further be provided with raw minimax and quiescence infrastructure, and would be able to recognize and prosecute a forced mate if it found one. However, it would be provided no heuristics. For example, it would not be told to open the game toward the center, nor to prefer rooks to knights, nor what is the Sicilian defense. It would have to infer such principles (or, conceivably, to discover better principles) on its own.
In its pure form, such a program would never be provided master games to study, but only its own games, played against itself. Only once fully self-trained would it be unleashed on human competition.
Does such a pure chess AI exist? Has a mechanical chess autodidact ever appeared? Indeed, can the old Turk teach himself?
(A tangentially related question has earlier appeared on this site, regarding the computerized study of chess openings.)
The question is graced by three different, illuminating answers at the time of this writing, by @WesFreeman, @GregE. and @Landei. All three are strongly recommended and I am going to feel guilty when, according to site policy, I formally accept one to the exclusion of the others. Let me here give thanks for and express my appreciation of all three.
Questions want brevity. A response to answers however might run longer. The interested reader therefore can skip from here directly to the answers and then, if still interested, can return to read the longer update that follows.
When I asked the question, I had in mind something like the following.
Suppose a hypothetical village on the outskirts of Shangri-La where the people have never heard of chess. During your brief visit, you teach the village elders the rules of the game, but never instruct them in any of the game's principles. Two of the elders play a game as the rest of the elders watch, while you (not wishing to disrupt the play by kibitzing) confine your commentary to questions of the rules. No postmortem follows the game, nor is chess played or discussed again while you are remain in Shangri-La. However, when you depart, never to return, you leave your chess set behind.
In your absence, the elders teach the game to the people. Some of the people later play a little during leisure hours, a few with growing enthusiasm, who fashion chess sets of their own.
It might not immediately be obvious to such villagers that a rook were better than a knight, but the people might still gradually work out the relative strengths of the chessmen over the play of many games. Likewise, it might not immediately be obvious to them that 1. a4 were a poor opening: they could but try it and consider the results.
To what extent would the villagers' understanding of the game eventually converge to that of the outside world? Lacking an opening book, might they develop novel openings of their own? Of course, one would not expect the villagers' openings to be very good at first but, given a couple of centuries of isolation, the villagers might develop a respectable opening repertoire, for all I know.
Would any of their openings, independently developed, prove interesting to the outside world, when the next traveler passed through to take note of them, 200 years later? Might Shangri-La give the world the new, novel, Shangri-La Defense?
If so, then, with respect to my original question on chess AI, what I had in mind was more or less this: could a chess AI more or less duplicate the chess progress of the villagers on the outskirts of Shanrgi-La?
Considering Sussman's story in @Landei's answer below, it is undoubtedly true that my villagers would bring certain preconceptions to the game. For example, they would bring an understanding that to possess more of a useful thing were generally better than to possess less of it, and therefore that to capture an opponent's chessmen were probably, usually preferable to suffering the capture of one's own. How territorial the fictional people of Shangri-La were by nature is a question for literature, but one can assume that they would recognize a position that commanded more space as superior to a position that commanded less. And any bright novice, once shown a chess set and instructed in the game's rules, can infer that a queen is likely better than a pawn, simply by that the queen has up to 27 moves available, whereas the pawn has no more than four -- and moreover, by speculative inference against the game's design, by the observation that a player begins with fewer queens than pawns.
My question therefore need not be construed to imply an absolute, Sussman-style injunction against bringing any kind of knowledge whatsoever to the chess board; but rather to imply a general injunction against preconceived, chess-specific knowledge. After all (disregarding the matter of the evolution of the game's rules long ago), at some time in the past, the first game of chess was played. Maybe the first player did open 1. a4; but eventually he learned better, and taught what he had learned to his disciples; who in turn learned more and taught more, generation by generation, to give us Kasparov.
Could an AI not do something like that, only in weeks rather than centuries?
Plato would be skeptical, I suppose. Hume would be more optimistic, but the question is no longer to be settled by philosophy alone. We have electronic computers now with which to test the proposition, and I was wondering what the state of the AI art was. The best chess AIs at present seem to be thoroughly unintelligent expert systems that beat everybody while intuiting nothing. I wondered whether slightly broader AIs that, in some sense, actually think about chess, had had any considerable success at teaching themselves the game.
I gather that the answer is no, probably not.