Author: Andrew Dados
Date: 10:47:13 07/19/00
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On July 19, 2000 at 10:21:19, Georg v. Zimmermann wrote: >Hi, > >I have huge problems with the horizon effect in my program (i.e. it sacks pawns >to push a queen loss far away). > >It is my understanding that these problems have been solved in modern chess >programs mainly because they reach high enough ply depths. > >Now imagine you were back in those times of much slower hardware : what can you >do to battle this problem ? > > >=== > >What I tried so far is > >I. big extensions on checks and captures >This even worsened the problem, and I don't understand why. > >II. detection of useless sacks >If a sack just lost material but didn't improve the positional eval old killer >moves (ply 2, opps turn) get extended to see whether the original threat was >really eliminated. This didn't work probably cause it is so complicated I had >too many bugs in it. > >=== > >Some background: > >I am playing around with a program that plays crazyhouse and bughouse, chess >variants where you can drop the pieces you captured from your opponent or your >partner captured from his opponent instead of a move. This increases the number >of possible moves by a lot (average maybe 33 in normal chess to over 110 in >crazyhouse/bughouse). This means you need an about 50 times faster computer to >reach 7 ply than in normal chess. Together with the nature of this game (games >are decided by king attacks) it makes for an exiting challence. When was the >last time you beat your program at 1 0 lightning/bullet time control ? :-) > >http://bughouse.net/info/index.htm#howtoplay ( Rules ) >http://home.att.net/~cferrante/chess/index.html ( Bughouse Problems ) I would try some form of selective search last few plys. With my very limited skill in bug I find that (as human) I extend on series of checks and if queen is en prise (other pieces are not worth go hunting after, you simply lose too many tempi). In zhouse I would add Rooks+Knights to valuable pieces. With null move you should catch threats on those pieces and extend accordingly. I wonder how you handle ever-changing list of pieces to drop in bughouse, btw. (you restart a search when partner gets you a new piece? Big headache...) Indeed a challenge - -Andrew-
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