Author: KarinsDad
Date: 14:56:35 08/06/99
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On August 06, 1999 at 13:59:10, Robert Hyatt wrote: [snip] > >It is a _long_ way from easy. The path has to go at least 100 plies beyond the >first capture/pawn push to make sure you won't run afoul of the 50 move rule >down that path. And to search that path is just a perfectly normal search, >which translates into _impossible_ to do... The databases don't contain trees, >they just contain a score for each possible position that can be reached... > >and I don't see any way to fold in the 50-move rule because of this... hence the >other thread and DTC scores... And even that won't work if the computer has to >'take over' a position played by a human, because then you can't assume optimal >play since reaching a database win, and at that point, the 50 move rule is >death to any sort of probe... > I now understand the difficulties involved (the "take over" case is probably not even worth discussing). My recommendation: punt. Chances are, even if you are playing another program with TBs, you will rarely find move by rep situations or violations of the 50 move rule once you get to the TBs. So, if you get to the TBs, it will either be a lose, a draw, or a win by default and the chances of it changing from a win to a draw (or a loss to a draw) due to either of these two rules should be extremely slim. Note: The move by rep problem can be minimized (but not eliminated) by using a little AI on choice of moves out of the tablebase. For example, if the white king has only been on f4 since the last capture or push (the reset for 50 move and for move by rep), then you could search the TB for moves that still mate, but start moving the white king away from f4 (or somesuch). Do you have statistics for Crafty on percentage of times (against computer opponents with TBs only) that a win (or a loss) was changed to a draw due to this (either for Crafty or for it's opponent)? KarinsDad :)
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