Author: Miguel A. Ballicora
Date: 08:45:22 05/06/02
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On May 06, 2002 at 00:01:22, Russell Reagan wrote: >On May 05, 2002 at 06:54:48, Uri Blass wrote: > >>how many possible positions are in 8*8 checkers? >> >>I think that there are only 32 squares and 4 kind of pieces and it means that >>5^32 is an upper bound for the number of position(a square may be empty) >> >>5^32 is only an upper bound and the number of practical positions to analyze may >>be clearly smaller. >> >>If you also remember that you probably do not need to search until the end of >>the game in order to play the best move then it seems that checkers is a game >>that is likely to be solved in the near future if it is not practically solved >>today. > >In addition to that, in draughts they have 8 man endgame tablebases as opposed >to the incomplete 6 man tablebases chess has. Since there are fewer pieces on >the board in draughts to begin with (24 in draughts, 32 in chess) this is even >more significant. > >In addition to THAT, there are (relative to chess) fewer moves to look at in >each position. Since each piece can only move to either 2 or 4 squares, it's >less. In addition to that, a lot of the moves are clearly losing after only a >few ply of search, so you have a lower branching factor, in addition to faster >move generation and search because of the simplicity of the game, you can search >deeper in a shorter amount of time (compared to chess). > >For example, a freeware draughts program searched to 13 ply in 0.86 seconds. >Fritz on my same machine takes 1 minute and 20 seconds to reach 13 ply. So, >chess's top programs can't search anywhere near as deep as a freeware draughts >program, and I imagine that Chinook probably reaches even greater depths than >this simple freeware draughts program. Fritz gets around 300 Knps on my machine, >and this simple draughts program gets 650 Knps. > >In a 1 minute search, Fritz reaches ply 12. Freeware draughts program reaches >ply 17 at 10 s. > >I personally don't see how any human could contend with even a simple draughts >playing program given it's more tactical nature than chess, but apparently >Marion Tinsley was able to contend with Chinook before he died, although I think >Chinook won the match. But I think Tinsley had one game where he forfeited or Tinsley won the first match. 2-3 years later, Tinsley forfeited the match for health reasons when the score was tied (all draws). That is how chinook become the #1, but it did not show superiority over Tinsley at that time. Regards, Miguel >something. I'm not sure what happened really. > >Russell
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