Author: Ricardo Gibert
Date: 19:16:40 10/03/99
Go up one level in this thread
On October 03, 1999 at 18:39:17, Robert Hyatt wrote: >On October 03, 1999 at 13:31:53, Ed Schröder wrote: > >>On October 03, 1999 at 09:32:47, Robert Hyatt wrote: >> >>>On October 03, 1999 at 04:42:40, Ed Schröder wrote: >>> >>>>>Posted by Lawrence S. Tamarkin on October 03, 1999 at 02:48:13: >>>>> >>>>>Congratulations to Rebel Century on its win against GM Scherbakov. We here at >>>>>the Marshall Chess Club Salute you! (I may just set up some match in the club, >>>>>involving an IM or GM, just for fun, but especially if Rebel company (Ed), >>>>>wants to draw a player from the NY chess mecca... >>>> >>>>You know I am always in for a challenge. And the Marshall Chess Club is >>>>quite a name to remember. >>>> >>>>>This makes me more excited about getting Rebel Century & studying with it (I >>>>>have long ago stopped playing with these programs), various positions out of >>>>>chess books, and my tournament games. Bigger book, custem levels, more >>>>>training features, test positons, utilities, etc, etc. It is definately a fantastic >>>>>bargain, that we (I), look forward too. >>>> >>>>Don't tell me about it. The data on the cd is 620 Mb. It was quite difficult to >>>>decide what should be left out as the limit is 640 Mb. How can one handle that >>>>in one year? I wonder. Seems to me DVD has the future and will be required >>>>within 2-3 years. >>>> >>>>>I hope Rebel Century will keep winning (No GM has yet lost in 30 moves or less >>>>>to it:)), and that the GM's pride will keep them coming back for more, rather >>>>>than fear scaring them away! >>>> >>>>We shortly discussed the possibility of a re-match. In principal we agreed to >>>>that but of course we have to figure out the details in email first. >>>> >>>>About the game: I am pretty impressed by the attacking style. It sacrifices >>>>a piece for a promising king attack. Then later counting the pieces on the >>>>board Rebel is behind a full rook. Still it shows +3.xx, a dream game. >>>> >>>>Ed >>> >>> >>>Rebel played well, obviously. However this is _not_ a sac. A sac is where you >>>give up material for positional gain. This is a pure tactical combination as >>>it wins more material than it gives up... >> >>What you describe is called a "positional sacrifice". I haven't used that >>word. It could have been an issue too as the evaluation for king safety >>in cases like yesterdays game is varying from 2-3 pawns and maybe more. >> >>Ed >> > >Most books on tactics define 'sacrifice' as giving up material for some sort >of compensation (either positional or long term tactical chances). They >define 'combination' as a sequence of captures resulting in a gain of material. No they don't. How about sac'ing a piece to obtain a perpetual or self-stalemate. These are sacs and are short term. They are also combos that lose material rather gain material. A combo can have anthing you can think of as an objective. Not just material gain. A combo is a series of forcing moves with a particular objective in mind. That is a common definition. Whether it is a satisfactory definition is a different issue. For practical and relatively unambiguous definitions, I suggest looking in Averbakh's book Chess Tactics for Advanced Players. An excellent book that treats the subject in an original and effective way. > >in this game, my material score is always > 0 in the position you give, meaning >that Crafty sees more material coming back to it than it gives up with the >original rook capture. That seems to better fit a 'combination'. Of course it does not drop below zero! Just about everyone can see Rebel has at least a perpetual! > >I will agree that several books talk about 'queen sacrifices' when they are >not really sacrifices... as giving up a queen to win the opponent's king gets >more material back than it gives up... Not really sacrifices? In common usage, the term is not really well defined so how can a move "really" be a sac or not for that matter when the term is not well defined? There is no "really". What it really boils down to is: a move giving up material is a sac when a strong player says it is. Of course that is not satisfactory, but that's the way it is. > >But I like the term 'combination' here... and usually use the term sacrifice >as in 'sacrificing the exchange'... after the rxc3 bxc3 type sac in many >Sicilian variations, black is 2 pawns (the exchange) down, yet gets lots >of compensation for that material, hopefully... Or in sacrificing a pawn >(such as playing a4-a3 to force your opponent to play bxa3 and end up with >three isolated pawns that you hope you can eventually win, and which you >_know_ can not be used to create a passed pawn... > >Mainly semantics... But if we call this a sacrifice, then I see one of these >every 2 games or so... IE QxR RxQ BxR, because after QxR RxQ I am definitely >down 4 pawns, but after the third move I am up a pawn... > >Bob > > > > >> >>>>>Larry - the chess software addict!
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