Author: martin fierz
Date: 12:51:13 05/21/03
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On May 21, 2003 at 11:58:55, Tom Kerrigan wrote: >On May 21, 2003 at 09:07:24, martin fierz wrote: >>connect 4 can be solved on a fast pc in 1 hour. checkers is nowhere near being > >Really? I didn't know that. Not by "brute force," i.e., only scoring positions >as win, lose, or draw. I believe that takes closer to a month. dead wrong! my connect 4 program is pure brute force with a large hashtable. 1 hour on a fast PC is enough for it to solve the game. it has an evaluation function, but in fact, it also has a search win mode, where the eval is turned off and it is a pure brute force searcher, that's faster in most cases! some other programs are even faster, maybe they have more intelligence :-) connect 4 was already solved back in approximately 1990 by james allen by pure brute force search (as well as by victor allis around the same time with a knowledgeable, rule-based program). i think he needed about 30 days back then. moore's law... >>solved IMO. it's much simpler than chess, and probably will be solved >>eventually, unlike chess. but for the moment, programming checkers is still a >>challenge :-) > >I remember maybe 5-6 years ago, Chinook would usually start hitting endgame >databases as soon as it got out of its opening book, and it wasn't much of a >contest to beat the 2nd best (now best) human player. So it might not be solved, >but it's still not the most interesting game ever anymore. it's funny that schaeffer complained about being confronted with the myth that samuel's program had solved checkers during his work on chinook. today, it's the same with chinook. of course it hit the endgame databases right after the opening book. but that alone means nothing - in checkers, captures are forced, and so you often encounter lines with mass exchanges. it doesn't mean the game is solved at all! many lines avoid these exchanges, and then you're on your own. the part about it wasn't much of a contest is wrong. chinook played two matches against don lafferty, number 2 of the world, after the second tinsley match was cancelled. the first match was tied with +1-1=18. the second match was won by chinook with 1 win in 40 games vs none. there is certainly not very much life left in checkers programming, but there is still much more left than most people think! the final version of chinook still made mistakes, but schaeffer didn't write about that in his book "one jump ahead" :-) cheers martin
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