Author: Uri Blass
Date: 14:47:51 01/05/04
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On January 05, 2004 at 17:06:41, Sune Fischer wrote: >On January 05, 2004 at 16:39:04, Uri Blass wrote: > >>I see that crafty is using swap_list[32] and I think that the array is too long. >> >>There are only 8 queen directions and 8 knight directions and I think that for >>practical cases swap_list[16] can make Crafty faster with no problems(in theory >>it is possible that 16 is not enough but I do not imagine a practical case when >>it can happen. > >I'm not sure 16 is enough if you consider some of those insane compositions >posted here from time to time :) > >I've no idea what the theoretical limit is, but probably not that far from 32. > >>I wonder if it is not better to have swap_list[16] in Crafty and add >>if (nc==15) break if you want to be careful not to crash maybe in 1 out of 1000 >>games. >> >>It seems to me that the price of allocating memory to 16 integer is higher than >>the price of one if (nc==15) inside the loop. > >IMO no. >It is better to be safe than sorry, such a bounds check can easily be avoided by >making the array a tad bigger. >In a non-smp program you can make the array static, if you like. I think that even if the price is that in one of 1000 games you get wrong see when the numbers of attackers is 16 or more than it then you will not be sorry. remember that usually one wrong evaluation is not enough to change the move. > >>Another point that I see is that it is using the value of the pieces and does >>not use piece square table. >> >>I wonder if there is a reason not to use piece square table to evaluate capture >>of pawn in the 7th as better than capture of pawn in the second rank. > >The problem is that Crafty prunes the losing captures. >By using piece square values BxN might be a losing capture by a fraction of a >pawn and not get searched. This is no problem and you can decide that losing capture is a capture that lose at least a pawn and losing 0.2 pawns is not enough. Uri
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