Author: Andrew Williams
Date: 15:32:58 06/01/01
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On June 01, 2001 at 16:13:41, Scott Gasch wrote: >Hi all, > >I have some questions about recapture extensions. > >First of all, what is the point? I assume to extend in a position where a >recapture move is the only reasonable move so as to see further beyond the >forced exchange. Somewhat like singular extensions or one legal reply >extensions, I think a properly done recapture extension should not be too >expensive. I'd also expect that a well done recapture extension would improve >the tactical strength of the engine. > >Well, I've been trying to get a good recapture extension working on my engine >for a while now. I've tried a bunch of different recapture definitions / >conditions. Most recently I did: > > 1. last move was a capture and this move captures the last moved piece > 2. this is the first capture considered (weighed by SEE) > 3. do not allow two recaptures in a row > 4. this move restores the material balance to what it was at the root. > >...in which case I extended 1/2 ply. Since I am expecting better tactical >ability with the recapture turned on, I test it with the ECM suite. Every time >I try, my results are worse with the recapture turned on than with no recapture. > Mine extends for a re-capture of a same-valued piece. In other words two consecutive captures where the values of the pieces captured were the same. Currently it's one ply in postmodernist. >I know that a bunch of other engines are doing recapture... so there must be a >good idea there somewhere. Can anyone address these questions or propose a >solid recapture condition? > >Thanks, >Scott Andrew
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