Author: Gerd Isenberg
Date: 14:06:10 03/10/03
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On March 10, 2003 at 14:49:30, Tom King wrote: >Hi all, > >One search extension which most programs seem to use is the passed pawn pushing >extension. When a move is made which is a passed pawn push to the 7th rank, we >extend the search by a ply. > >My programs has got away without this extension for years. Or perhaps "got away" >isn't right.. there have been losses which this extension might have prevented. > >Anyway, what do people think of this extension. Worth having? If so, what value >would you attach to it? > >Regards (and hi to all), >Tom >tom@silentshark.co.uk Hi Tom, i do some fractional extensions with passers. Not only if they push or capture foreward to the 6th or 7th rank, even if a opposite "guard" pawn in backward or knight distance (re)captures (but no push) from it's base rank (own 7th rank) to the "right" side, which establish an own passer on the 6th rank. I consider the number of advanced passers per side, supporting and defending pieces. A lot of code, specially at interiour nodes or near the root to look for further recuductions of determined extensions. Even if these extensions work fine in some testpositions, i requires a lot of effort to tune them for tournament play. Most often i do it by "gut feel". One thing i tried to control extensions with is to vary the amount of fractions to become one ply. I tried to vary it by search depth and by the relative amount of extensions so far. Regards, Gerd
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