Author: Ross Boyd
Date: 16:35:58 01/25/06
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On January 25, 2006 at 08:40:39, James Swafford wrote: >On January 25, 2006 at 04:19:17, Ross Boyd wrote: > >>On January 25, 2006 at 01:34:54, Joseph Ciarrochi wrote: >> >>>We learn early on that if we have a winning advantage, we want to eliminate any >>>chance of counterplay by our openent. We usually would like to simplify the >>>position. >>> >>>I've noticed that rybka and other engines often won't simplify the position , if >>>there is the slightest loss of points (say -.1). So lets say black and white >>>still have q's on the board, but black has a clearly winning advantage (+6). if >>>black gets the chance, it should trade those queens (assume this really is a >>>good idea). >>> >>> >>>Are there any engines that will do this?, i.e., take a slight decrease in >>>advantage to simplify the position and garuntee the win? >> >>Hiarcs springs to mind.... it will occasionally throw away material to simplify >>into an easy win. You will see this kind of behaviour in most engines that use >>egtbs... ie. they will throw wood to get a tablebase win/mate. >> > >I've observed this behaviour (even in my own stuff), and it's not because >of any programming-for-simplification. It's just a side effect of the >search seeing a win from TB's with N men on the board, and having to >throw one away to reach that position since it doesn't have N+1 men TB's. > >Not quite the same as gracefully simplifiying down... > >-- >James No, not graceful but certainly effective at wrapping up a game quickly. :-) Another related area is how engines handle egtb draws. Mine is incredibly ignorant and simply chooses randomly between moves that maintain the score so it quite happily gives away material when the position is drawn. This is really due to laziness on my part... and I'm certain it has cost half-points against engines which don't have egtbs and could misplay an ending. A good example is KRKB endings. In most cases its a draw... so my engine will occasionally sac the rook for nothing to leave a drawn lone K v B ending. How dumb is that? All that is required is some code at ply 0 to avoid sacrificing/swapping its pieces when material is a plus and the egtbs are saying its a dead draw. I guess my only excuse is that there are higher priority tasks to work on when developing an engine. Ross
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