Author: Peter McKenzie
Date: 11:47:19 05/23/02
Go up one level in this thread
On May 23, 2002 at 05:13:42, Andrew Williams wrote: >On May 23, 2002 at 03:40:29, Steve Maughan wrote: > >>I have recently been tinkering with threat extensions (TE). I'd definitely like >>to include some form of TE but I have encountered some problems of tree >>explosion. >> >>What is happening is that the null move routine is detecting a mating threat and >>I'm extending by one ply at ply[x]. I then try a move (at ply[x]) that doesn't >>aviod the threat. In reply the opponent plays a sub-optimal move at ply[x+1] >>that does not lead to mate even though a forced mating move does exist. At >>plt[x+2] I then detect a threat and extend again... >> >>This sequence leads to a tree explosion. Is there any common wisdom as to how >>to avoid this? Some ideas that I've had are: >> >>1) Only extend by a fraction - inelegant solution IMO >>2) Store the rely to the null move that gave the checkmate and make this the >>Killer move for the next ply - didn't seem to work well - still some tree >>explosion. >> >>Has anyone any ideas? >> >>Thanks, >> >>Steve > >Why not restrict your search to one threat extension per line? ie Keep track of >whether you've had a TE in the current path, and if so don't check for it again. I do this in Warp, and I'm not that happy with the it. Its seems pretty artificial, and doesn't scale well with deep searches. I'm planning to try partial ply pretty soon. I suspect Steve has a move ordering problem though. An interesting issue. > >Andrew
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