Author: Robert Hyatt
Date: 21:06:31 01/25/01
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On January 25, 2001 at 23:49:07, Robert Hyatt wrote: >On January 25, 2001 at 21:35:10, Will Singleton wrote: > >>On January 25, 2001 at 09:41:41, Robert Hyatt wrote: >> >>>On January 25, 2001 at 00:16:04, Andrew Dados wrote: >>> >>>>Thanks Bob for very interesting report. >>>>A couple of loose thoughts... >>>> >>>>Recapture extension is intuitively no good for tactical suite for a simple >>>>reason: all tactical lines give up temporarily material. And lines with >>>>exchanging down pieces are not 'beautiful' for humans - which was probably one >>>>of conditions for selecting a 'tactical' position into set like WAC. >>>> >>>>It is hard to say if your program plays weaker or stronger in practical games >>>>because of it. And, btw, one of Craftys strengths is exchanging down to won >>>>endgame. Maybe some sort of nunn-type match between 2 versions can give more >>>>data about it? >>>> >>>>And if you come down to think about the trend - It would be interesting to run >>>>your test with recapture extension going below zero....:) >>>> >>>>-Andrew- >>> >>>Ken Thompson got me started on this in the early 80's. The idea is that >>>if you are in some kind of trouble (say losing a pawn) then one way to help >>>"hide" this is the good old BxN PxB sequence. BxN forced the opponent to >>>recapture the bishop, and that eats two plies of your total search, maybe >>>hiding the pawn loss. Extending a ply partially offsets this... >>> >>>But I have never tested it very thoroughly. I am going to turn it off on >>>one version and play an extended match, 2cpus to 2cpus.. I'll report on the >>>result later.. >> >>I predict the capture extension version will win easily, especially in medium >>blitz games (5 0). I have done that test (but not the wac test), and my program >>definitely plays better with a limited capture extension. > > >I have run 3 100 game matches so far. In the first, the recapture extension >won by a small margin. IN the second, it lost by a big margin. In the third.. >can't report yet... 3 more games to go... > >I am playing fairly fast blitz games which is where I generally see the best >results for extensions... > >More data in a bit... \ 300 games... 3 sets of 100 games played at 40 moves in 1 minute, each program getting 2 cpus, ponder=on, etc... match 1. recap wins 26-18 with rest draws. match 2, recap loses 3-20 with rest draws. match 3, recap loses 6-21 with rest draws. games were played with learning=off, without a books.bin/bookc.bin to get a bit of variety...
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