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Subject: Threat Extension and Tree Explosion

Author: Steve Maughan

Date: 00:40:29 05/23/02

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

• Re: Threat Extension and Tree Explosion Vincent Diepeveen 07:10:32 05/24/02
• Re: Thanks Everyone!! Steve Maughan 23:34:22 05/23/02
• Re: Threat Extension and Tree Explosion Miguel A. Ballicora 09:53:40 05/23/02
  • Re: Threat Extension and Tree Explosion Peter McKenzie 15:37:59 05/23/02
    • Re: Threat Extension and Tree Explosion Steve Maughan 23:29:45 05/23/02
• Re: Threat Extension and Tree Explosion stuart taylor 04:25:01 05/23/02
• Re: Threat Extension and Tree Explosion Andrew Williams 02:13:42 05/23/02
  • Re: Threat Extension and Tree Explosion Peter McKenzie 11:47:19 05/23/02
    • Re: Threat Extension and Tree Explosion Scott Gasch 16:21:34 05/23/02
      • Re: Threat Extension and Tree Explosion Scott Gasch 19:50:02 05/23/02

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