Author: Pekka Karjalainen
Date: 08:14:45 05/05/02
Go up one level in this thread
On May 05, 2002 at 06:54:48, Uri Blass wrote: [...] >>3) dominated by computers >> >>8x8 checkers, 8x8 othello >> >>where the top humans have not been able to demonstrate ability to beat the >>computer for some time, yet the games are not yet solved or likely to be solved >>in the near future. > >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. The question is also considered in Jonathan Schaeffer's book _One Jump Ahead_, and the Chinook webpages contain this info about the numbers. http://www.cs.ualberta.ca/~chinook/databases/databases.html > >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. I agree. It seems that the motivation to improve Chinook was lost when Tinsley retired from competitive checkers and passed away. There simply were no strong enough human players to take his place and challenge the computer anymore. I don't want to guess how much effort it would take to actually solve the game-theoretic value of the checkers starting position. Certainly it would seem that bigger endgame databases could be constructed than the present 8-piece ones available at the above URL, but perhaps it is really a question of "why bother now?" > >In chess it is easy to find for every program a legal position when it cannot >find the right move in a reasonanble time. > >I do not know if it is possible to do it in checkers for chinook and even if >it is possible then it does not mean that the game is not practically solved >because if you cannot get that position in a game against chinook then the >position is not relevant. I think it is safe to say that for human vs. computer play checkers is practically solved by computers, since there is no-one to take TInsley's place. Perhaps there are some positions where humans have more knowledge than Chinook, but they must be very rare now. >>B? Can you explain? Does the term positional play in draughts have any >>relation to positional play in chess, since they are two completely different >>games? > >I know nothing about draught but I can explain the meaning of more tactical >game. > >A tactical game is a game when search is relatively more important and >a positional game is game when the evaluation function is more important. > >If searching one ply deeper gives almost nothing in rating the game is not a >tactical game. > >I understood that it is the case in go. This is a workable definition from computer point of view. However, if diminishing returns are really a fact of computer chess at higher ply depths, does it mean it turns less tactical when computers search deeper? Perhaps that is true in a way. Also, I think Vincent Diepeveen or some other draughts program creator (is Vincent still working at draughts at all?) said that currently increasing the search depth of draughts programs does very little for their strength. They just have these certain "positional" weaknesses no matter what... I don't know much about this, so I better stop talking of things I do not understand :) Perhaps it is fair to say that chess has more tactics and strategy than draughts in that the number of concepts and general complexity is higher. However, in draughts the relative balance may be a little more weighed towards strategy. OK, this is really a computer chess forum, so I shall stop now. > >Uri Pekka
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