Author: Uri Blass
Date: 11:09:38 09/06/00
Go up one level in this thread
On September 06, 2000 at 13:56:42, Robert Hyatt wrote: >On September 06, 2000 at 11:18:53, Uri Blass wrote: > >>On September 06, 2000 at 11:06:16, Robert Hyatt wrote: >> >>>On September 06, 2000 at 06:14:29, Amir Ban wrote: >>> >>>>On September 05, 2000 at 10:32:27, Robert Hyatt wrote: >>>> >>>>>On September 05, 2000 at 01:18:55, Mark Longridge wrote: >>>>> >>>>>>I was playing crafty the other day and white had a pawn on h7, and a knight on >>>>>>g5, black's king is in the corner, and black has only it's king. >>>>>> >>>>>>There's absolutely no way black can win with just a king, but it STILL REFUSES >>>>>>A DRAW request! >>>>>> >>>>>>It just seemed very odd ;-) >>>>> >>>>> >>>>>It mainly depends on how you have things set up. And even if it is set up >>>>>correctly, there are 'rules' that have to be satisfied before it will accept >>>>>a draw. IE it has to believe it is a draw. It also has to get a draw score >>>>>back from the search for 5 consecutive moves (3 for GM players) before it will >>>>>accept or offer a draw. >>>>> >>>>>Just giving the position doesn't provide enough information... >>>>> >>>>>The log.nnn file is also needed. >>>> >>>>The position provides all the relevant information. >>>> >>>>It's your problem, not the opponent's to make sure your program behaves >>>>reasonably. >>>> >>>>Asking the opponent to provide internal crafty parameters and logs is not >>>>reasonable. >>>> >>>>Amir >>> >>> >>>Your assumptions are wrong. The default setup _will_ offer draws. But it is >>>possible that the user has disabled this and not remembered. The position >>>doesn't say a thing, because of the rules I gave. Crafty has to find a draw >>>score 5 moves in a row to offer a draw. The current search eval has to be >>><= drawscore for it to accept a draw, and it won't accept a draw at all during >>>the first 30-40 moves of the game. Based on that, I can't look at a position >>>and say whether it should have accepted a draw offer there or not... It might >>>have accepted after 4 more moves... who knows without seeing what went on in >>>the _game_... >> >>This is a logical explanation for the fact that crafty did not agree to a draw >>but better rules should tell it always to accept a draw if it has only a king. >> >>Uri > > >It should, unless it has been disabled by the user. I can't see any way to >reach a king only position without crafty seeing it in the search a few moves >ahead of time. I agree that cases when crafty did not see a draw or a loss for itself in the last few moves are not common but I am not sure if they are impossible. The only cases that I can think about(assuming that there are no unknown bugs) are: 1)A case when crafty cannot see something because of null move pruning. 2)A case when crafty believed 5 moves ago that another line was leading to a win and only later understood that it is not good and had to sacrifice to get a draw position when it has only a king. Uri
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