Author: Alessandro Damiani
Date: 10:40:09 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 Hi Peter, the current version of Fortress has a new kingsafety (finally stable :). On a Celeron 333MHz with a hashtable of 16.8MB: depth score time nodes PV --------------------------------------------------------- 1 43 100 3 Bf4-g3 1 163 100 41 Bf4xh6 g7xh6 Qd2xh6 1 163 100 54 Bf4xh6 g7xh6 Qd2xh6 2 163 100 98 Bf4xh6 g7xh6 Qd2xh6 2 163 100 157 Bf4xh6 g7xh6 Qd2xh6 3 136 100 680 Bf4xh6 g7xh6 Qd2xh6 3 136 100 2302 Bf4xh6 g7xh6 Qd2xh6 4 144 100 3063 Bf4xh6 g7xh6 Qd2xh6 Be6-g4 4 144 100 5552 Bf4xh6 g7xh6 Qd2xh6 Be6-g4 5 161 100 10437 Bf4xh6 g7xh6 Rf2-f6 Nc6-e5 Rf6xh6 Ne5xd3 c2xd3 5 161 100 51757 Bf4xh6 g7xh6 Rf2-f6 Nc6-e5 Rf6xh6 Ne5xd3 c2xd3 6 203 200 103241 Bf4xh6 Nc6-e5 Qd2-g5 Ne5-g6 Bd3xg6 f7xg6 6 203 300 194070 Bf4xh6 Nc6-e5 Qd2-g5 Ne5-g6 Bd3xg6 f7xg6 7 221 500 298566 Bf4xh6 Nc6-e5 Qd2-g5 Ne5-g6 Bh6xg7 Kg8xg7 Rf1-e1 7 221 1500 1082327 Bf4xh6 Nc6-e5 Qd2-g5 Ne5-g6 Bh6xg7 Kg8xg7 Rf1-e1 8 195 1900 1382502 Bf4xh6 Nc6-e5 Qd2-g5 Ne5-g6 Qg5-h5 g7xh6 Bd3-e2 Be6xc4 8 195 4900 3464042 Bf4xh6 Nc6-e5 Qd2-g5 Ne5-g6 Qg5-h5 g7xh6 Bd3-e2 Be6xc4 9 210 6500 4693571 Bf4xh6 Nc6-e5 Bh6-g5 Re7-d7 Rf1-e1 Ne5xd3 c2xd3 Rd7-d4 Qd2-b4 Rd4xd3 Qb4xb7 9 210 18500 12917713 Bf4xh6 Nc6-e5 Bh6-g5 Re7-d7 Rf1-e1 Ne5xd3 c2xd3 Rd7-d4 Qd2-b4 Rd4xd3 Qb4xb7 10 247 40000 28328148 Bf4xh6 f7-f6 Bh6xg7 Re7xg7 Rf2xf6 Be6-f7 Rf1-e1 Qe8-f8 Qd2-f4 Ra8-c8 10 247 64500 44808241 Bf4xh6 f7-f6 Bh6xg7 Re7xg7 Rf2xf6 Be6-f7 Rf1-e1 Qe8-f8 Qd2-f4 Ra8-c8 The new version will be out soon. Alessandro
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