Computer Chess Club Archives




Subject: Capture/recapture extensions

Author: Andrew Williams

Date: 02:34:41 12/14/98

Hello all,

I'm trying to work out how to implement capture/recapture extensions in
my program. I have had a look at crafty and gnuchess and I've tried
several approaches, viz:

1 Extend when a capture followed by recapture restores the material
  balance we had at the root.

2 Extend when the capture/recapture restores the material balance from
  before the sequence.

3 Extend when the capture and recapture are on the same square (and same
  material value).

In all these cases, I seem to get a much larger tree and often lose a ply
of search because of this. So, three questions:

(a) Am I on the right lines with 1, 2 and 3 above?
(b) Is it normal to lose depth when doing this?
(c) Generally speaking, it better to complete d7 with this extension than
    d8 without it?

I realize that these questions probably aren't yes/no style questions, so
thanks to anyone who takes the trouble to reply.


Andrew Williams
(Author of PostModernist on ICC)

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