Author: Heiner Marxen
Date: 01:23:56 10/04/01
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On October 04, 2001 at 01:52:13, Timo Saari wrote: >I am rewriting an old chess problem solver program and as of now it can solve >normal mate in n moves type problems when n is not too large. Hi Timo, Welcome to the club! There are not many members in this club apart from you and me and Leonid. >It does a brute >force type search and uses a hash table and killer heuristic. I assume that in >order to make it reasonably fast with more challenging problems (n>6) I need to >implement at least move ordering and perhaps special handling of plies near the >leaves of the search tree. Some quick remarks: If you want to quickly find all shortest solutions, you have to stick to a brute force type search. If you want to quickly find some solution, may be not of minimal depth, this is completely different. Then extensions or restricted types of search help a lot. Some chess playing programs are quite good at this (e.g. Chessmaster) and often still find a minimal depth solution. But there is no guarantee for minimal depth. hash table... yes, with increasing depth it provides increasing speedup. Depth=4 (mate in 4) is the break even point. killer heuristics... can help the defender while its move ordering is not so good. It rarely helps the attacker side, although there are exceptions. move ordering... very important for the defender. For the attacker a very simple move ordering (check moves first) is ok. special handling of the last plies... is very important. It can gain a lot of linear speedup, but also involves a lot of hard to write code. You already catched most speedup ideas. >Can somebody point me to any existing information on abovementiond topics? Sure... Have a look at my problem solver "Chest" at http://www.drb.insel.de/~heiner/Chess/ It comes with sources. There is a link to Dann Corbit's site, where you can download a Win32 executable. >Any help appreciated. > >Timo Have a lot of fun developing your own program! Heiner
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