Author: Robert Hyatt
Date: 19:34:54 10/03/99
Go up one level in this thread
On October 03, 1999 at 22:16:40, Ricardo Gibert wrote: >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. > my webster's defines 'sacrifice' as 'voluntarily giving up something of value'. I have a hard time saying 'I will sacrifice a ten-dollar bill if you will give me a 20 dollar bill in return...' :) But I don't object to the term being used.. I just think that for a computer, the concept 'sacrifice' is wrong. It is just a perfectly computable combinational tree search... Bob >> >>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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