Author: Ed Schröder
Date: 16:00:25 11/29/99
Go up one level in this thread
>Posted by Robert Hyatt on November 29, 1999 at 15:11:39: > >In Reply to: Re: Positional/Real Sacrifice posted by Paulo Soares on >November 29, 1999 at 03:02:23: > >On November 29, 1999 at 03:02:23, Paulo Soares wrote: > >>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 >> >>I agree with you, this is a valid sacrifice. >> >>Rebel Century(note that anti-GM=stronger)- PIII-450 >> >>First Position: >> >> +---+---+---+---+---+---+---+---+ >>8 | *R| | | | *Q| | *K| | >> +---+---+---+---+---+---+---+---+ 00:00:00 00:00:00 >>7 | *p| *p| *p| | *R| *p| *p| | >> +---+---+---+---+---+---+---+---+ >>6 | | | *N| | *B| | | *p| Time infinite >> +---+---+---+---+---+---+---+---+ Hash 60 Mb >>5 | | | | | | | | | Engine Rebel Century >> +---+---+---+---+---+---+---+---+ Personality Rebel Century >>4 | | | p | | | B | | | anti-GM Strong >> +---+---+---+---+---+---+---+---+ System Tiger Off >>3 | | | | B | | | | | Combination Off >> +---+---+---+---+---+---+---+---+ Style Normal >>2 | p | p | p | Q | | R | p | p | Strength Strongest >> +---+---+---+---+---+---+---+---+ Search Normal Search >>1 | | | | | | R | K | | >> +---+---+---+---+---+---+---+---+ >> a b c d e f g h >> >>r3q1k1/ppp1rpp1/2n1b2p/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - >> >>[Event "?"] >>[Site "?"] >>[Date "??.??.????"] >>[Round "?"] >>[White "Peter3"] >>[Black ""] >>[Result "*"] >>[WhiteElo "?"] >>[BlackElo "?"] >>[FEN "r3q1k1/ppp1rpp1/2n1b2p/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - 0 1"] >> >>1.* >> >>00:00:00 1.00 1.02 1.Bxh6 gxh6 2.Qxh6 > > > >This looks _incredibly_ dangerous. For every position where Bxh6 works, >there are 10 positions where Bxh6 loses. Here a piece for two pawns looks >awful if the other pieces can't get over to help out... Speculative play is >nice, as in the old days of the Novag gadgets from Kittinger, and in the >current >play of CSTal... but it can backfire big-time as well... > >Crafty doesn't like the sac, unless it sees actual material coming back, >because >I have spent a lot of time teaching it which types of material imbalance are >bad and which types are good. A piece for 2 pawns is always bad unless there >is some tactical conclusion at the end. And given the above PV there >obviously >isn't anything except a somewhat naked king position for black... I can not believe you saying this. After 1.Bxh6 gxh6 2.Qxh6 there is a queen, 2 rooks and a bishop all pointed very dangerous at a naked king. Rebel giving +1 is fully justified. Every 1800 rated chess player will play 1.Bxh6 immediately, no need to calculate. Ed > > > > >>00:00:00 2.00 0.43 1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 Bxc4 >>00:00:00 3.00 0.62 1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 >>00:00:00 4.00 1.18 1.Bxh6 f6 2.Be3 Rd8 >>00:00:01 5.00 1.05 1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 Bxc4 >> 4.Bg6 Qd7 (0) >> >>00:00:02 6.00 1.11 1.Bxh6 f6 2.Be3 Ne5 3.Qc3 Nxd3 4.Qxd3 >> Rd8 (1) >> >>00:00:06 7.00 1.02 1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 Bxc4 >> 4.Bg6 Qd8 5.Rd2 (4) >> >>00:00:28 8.00 1.10 1.Bxh6 f6 2.Be3 Rd7 3.Qc3 Rad8 4.b4 >> Qh5 (13) >> >>00:01:27 9.00 1.28 1.Bxh6 f6 2.Rxf6 gxf6 3.Rxf6 Qd7 >> 4.Qg5+ Kh8 5.Bf8 Rh7 6.Bxh7 (41) >> >>00:04:09 10.00 1.26 1.Bxh6 f6 2.Rxf6 gxf6 3.Rxf6 Qd7 >> 4.Qg5+ Kh8 5.Bf8 Qd4+ 6.Kh1 Rh7 (135) >> >>00:20:39 11.00 1.71 1.Bxh6 Qf8 2.Qg5 Rd7 3.Rf3 Rad8 >> >>Positions : 182.640.681 >>Nodes per second : 136.502 >> >>Extensions (checks) : 7.804.673 (4%) >>Extensions (captures) : 3.739.854 (2%) >>Extensions (king safety) : 701.204 (0%) >>Extensions (on depth) : 5.358.611 (2%) >>Extensions (remaining) : 162.555 (0%) >>Extensions (total) : 17.766.898 (9%) >> >>Hash Table : 1.517.447 1.188.944 (99%) >>Average depth : 12 >>Deepest depth : 53 >> >> >> >>Second position: >> >> +---+---+---+---+---+---+---+---+ >>8 | *R| | | | *Q| | *K| | >> +---+---+---+---+---+---+---+---+ 00:00:00 00:00:00 >>7 | *p| *p| *p| | *R| *p| | | >> +---+---+---+---+---+---+---+---+ >>6 | | | *N| | *B| | | Q | Time infinite >> +---+---+---+---+---+---+---+---+ Hash 60 Mb >>5 | | | | | | | | | Engine Rebel Century >> +---+---+---+---+---+---+---+---+ Personality Rebel Century >>4 | | | p | | | | | | anti-GM Strong >> +---+---+---+---+---+---+---+---+ System Tiger Off >>3 | | | | B | | | | | Combination Off >> +---+---+---+---+---+---+---+---+ Style Normal >>2 | p | p | p | | | R | p | p | Strength Strongest >> +---+---+---+---+---+---+---+---+ Search Normal Search >>1 | | | | | | R | K | | >> +---+---+---+---+---+---+---+---+ >> a b c d e f g h >> >>r3q1k1/ppp1rp2/2n1b2Q/8/2P5/3B4/PPP2RPP/5RK1 b - - >> >>[Event "?"] >>[Site "?"] >>[Date "??.??.????"] >>[Round "?"] >>[White "Peter10"] >>[Black ""] >>[Result "*"] >>[WhiteElo "?"] >>[BlackElo "?"] >>[FEN "r3q1k1/ppp1rp2/2n1b2Q/8/2P5/3B4/PPP2RPP/5RK1 b - - 0 1"] >> >>1..* >> >>00:00:00 1.00 -3.50 1..Bxc4 2.Bxc4 >>00:00:00 1.01 -0.98 1..Nd4 >>00:00:00 1.03 -0.89 1..Rd8 >>00:00:00 1.18 -0.85 1..Qf8 >>00:00:00 1.24 -0.13 1..f5 2.Bxf5 Bxc4 >>00:00:00 2.00 -0.85 1..f5 2.Bxf5 Bxc4 3.Bg6 Qd7 >>00:00:00 3.00 -0.58 1..f5 2.Bxf5 Bxc4 >>00:00:00 4.00 -0.45 1..f5 2.Bxf5 Bxc4 3.Bg6 Qc8 4.Ra1 >> Nd4 (0) >> >>00:00:00 5.00 -0.72 1..f5 2.Bxf5 Bxc4 3.Bg6 Qd8 4.Rd2 >>00:00:01 6.00 -1.46 1..f5 2.Bxf5 Bxf5 3.Rxf5 Re5 4.Rf6 >> Qd7 (1) >> >>00:00:09 7.00 -1.89 1..f5 2.Bxf5 Nd4 3.Bd3 Nc6 4.Bg6 >> Qd8 (5) >> >>00:00:21 8.00 -2.63 1..f5 2.Bxf5 Nd4 3.Bd3 Rg7 4.c3 >> Nc6 5.Rf8+ Qxf8 6.Qxe6+ Rf7 7.Qg6+ >> Rg7 (12) >> >>00:00:45 9.00 -3.00 1..f5 2.Bxf5 Nd4 3.Bd3 c5 4.Rf6 >> Rg7 5.c3 (36) >> >>00:01:15 10.00 -3.27 1..f5 2.Bxf5 Nd4 3.Bd3 Rg7 4.Rf4 >> Rd8 (56) >> >>00:03:21 11.00 -3.03 1..f5 2.Bxf5 Nd4 3.Bd3 Rg7 4.c3 >> Nc6 5.Rf8+ Qxf8 6.Qxe6+ Kh8 7.Rxf8+ (133) >> >> >>Positions : 24.825.096 >>Nodes per second : 118.780 >> >>Extensions (checks) : 3.893.161 (15%) >>Extensions (captures) : 427.768 (1%) >>Extensions (king safety) : 121.776 (0%) >>Extensions (on depth) : 269.512 (1%) >>Extensions (remaining) : 27.516 (0%) > >>Extensions (total) : 4.739.733 (19%) >> >>Hash Table : 470.761 688.827 (84%) >>Average depth : 13 >>Deepest depth : 58 >> >>Paulo Soares, from Brazil
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