Author: Ed Schröder
Date: 00:08:54 12/01/99
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>Subject: Re: Positional/Real Sacrifice > > > [ Post Followup (without quoting) ] [ Post Followup (with >quoting) ] [ Computer Chess Resource Center ] [ CCC Home Page ] > > >Posted by Robert Hyatt on November 30, 1999 at 17:43:50: > >In Reply to: Re: Positional/Real Sacrifice posted by Ed Schröder on >November 30, 1999 at 03:35:54: > >On November 30, 1999 at 03:35:54, Ed Schröder wrote: > >>>Posted by Robert Hyatt on November 29, 1999 at 20:17:47: >> >>[ snip ] >> >>r3q1k1/ppp1rpp1/2n1b2p/8/2P2B2/3B4/PPPQ1RPP/5RK1 w - - bm Bxh6; >> >>>>>>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... >> >>1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 the black king is even more naked. I guess >>we have a different view on king safety. > > > >I probably have as big (or bigger) king safety scores as you. However, I >have a big penalty for trading a piece for 2-3 pawns, as it almost always >loses unless tactics make it work... > >>>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... >> >>Who was the IM? >> >>After 1.Bxh6 gxh6 2.Qxh6 f5 3.Bxf5 I am pretty sure all programs soon will >>display a +2 or +3 score. > > >Note that I didn't say it doesn't work. I said that at the shallow depth >of 1-2-3-4 plies, it looks _very_ dangerous to do this.. because black has >some defensive resources that don't look obviously bad until you search >deeper. > >That was my point... that tossing a piece for 2 pawns, with no concrete idea >of whether it will work or not, seems dangerous. IE what if we move a couple >of black pieces, leaving white's pieces as is. It won't be too hard to (say) >move the second black rook so that it helps the other rook defend... and one >more black piece in the game and the attack doesn't work at all... All kind of aspects of king safety are microscoped before Rebel finally decides to give a 2 pawn bonus for the position after 2.Qxh6 this includes blacks defence possibilities to escape from the king attack as well. >Would you _still_ play the sac? That is the danger. I definitely would want >to play it in blitz. And I definitely wouldn't want to play it in a 40/2hr >game knowing that the GM has all the time in the world to find the refutation. You mean me personally, a 1800 player? I would play 1.Bxh6 without any hesitation as my intuition says it wins. Only in blitz I would ruin it because the position because of time pressure but that's another story :) >> >>Based on this I wouldn't call this position a 100% positional sacrifice as >>it is somewhere in the 10th ply area (depending on a programs extension >>use).\ > > >Somewhere around 3 minutes crafty fails high on Bxh6. So it probably does >work tactically based on that. But you liked it at ply=1, which was the thing >that seemed dangerous... because at ply-1 it is _definitely_ based on >position >alone.. True and I like it. Ed
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