Author: Andrew Williams
Date: 09:13:26 11/29/99
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On November 29, 1999 at 00:32:17, Peter McKenzie wrote: >The following position is from a blitz game between Hossa and Beadle (LambChop) >on ICC: > >r3q1k1/ppp1rpp1/2n1b2p/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - > >Hossa played Bxh6 and wiped Beadle out. This position is an interesting test of >king safety evaluation, as there is no short range mate or win of material after >the sac although I'm pretty confident the sac is correct. > >I tried this position with LambChop, and it too liked Bxh6 giving it a score of >about +0.5 pawns from depths 4 thru 8. On depths 9-10 it switched to Qc3 with a >similar score of around +0.5, then at depth 11 it switched back to Bxh6 and the >score jumps to +1.4. Depth 12 is still Bxh6 at +1.6. > >We discussed this position a bit on ICC, Bob ran it on Crafty which didn't want >to play Bxh6. Peter Kappler ran it on Hiarcs which liked Bxh6 straight away >with a +1 score! Diep also liked Bxh6 from early on, and had an even higher >score. I wonder what Hiarcs and Diep are doing in eval that Crafty isn't... or >vice-versa. > >How about other programs? >What do the human chess experts think? > >If that position is too hard, it might be productive to play down the main line >of accepting the sacrifice. So after 1.Bxh6 gxh6 2.Qxh6 we have: > >r3q1k1/ppp1rp2/2n1b2Q/8/2P5/3B4/PPP2RPP/5RK1 b - - > >Here LambChop gets a score jump from -0.2 at ply 7 to -1.7 at ply 8. Not quite >sure why :-) > >cheers, >Peter Peter, This is a really good example. Thanks for posting it. I tried PostModernist on the first position. I have just been messing about with my King Safety again and it may be a bit too aggressive. But it finds Bxh6 at depth 3 and sticks with it at least until depth 11. At this stage it has a score of +1.13. As for the second position, mine says +4.83 at d11 after gxh6. Andrew
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