Author: Robert Hyatt
Date: 17:01:16 08/06/99
Go up one level in this thread
On August 06, 1999 at 17:56:35, KarinsDad wrote: >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. I agree... but note that many are not going to like this, perhaps yourself included, when you want to analyze some endgame you played to see what will happen after the game is resumed... But I don't see a real solution to this problem... > >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. that's debatable... since the losing side also has TBs, it will certainly put off the loss as long as possible, which might cause problems (ie in Eugene's kbn vs kn mate in 100+ position). And if the DTC value is ever added, I'd certainly be checking it when I was losing, to always take a move with DTC+ current-50-move-counter > 50, to ensure a draw in a technically won ending. :) > >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 :) I don't believe it has ever happened, at least not that I have seen. Bob
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.