Author: Robert Hyatt
Date: 17:17:47 11/29/99
Go up one level in this thread
On November 29, 1999 at 19:00:25, Ed Schröder wrote: >>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. > Sorry, but _I_ am an 1800+ player and _I_ wouldn't play it immediately. Because black can play f5, and it doesn't look nearly so clear after that. The king has a way out... the black rook now can interpose on the g/h files. The f file is no longer useful unless white does something else... It may be good. It may not work. But as a human, I don't play Bxh6 here without calculating something worthwhile at the end of the sequence. I let an IM look at this for several minutes... he left unclear whether it was good or not... That is what I meant by "this looks incredibly dangerous". Because if you don't get something back from this, you are pretty well sunk. The position looks pretty nice for white. But good enough to toss a piece immediately? Unclear without a lot more analysis... to me >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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