Author: Lanny DiBartolomeo
Date: 22:17:57 10/05/99
Go up one level in this thread
On October 06, 1999 at 00:06:54, blass uri wrote: >On October 05, 1999 at 11:40:27, Lanny DiBartolomeo wrote: > >>On October 05, 1999 at 11:15:35, blass uri wrote: >> >>>On October 05, 1999 at 10:23:46, Lanny DiBartolomeo wrote: >>> >>>>On October 03, 1999 at 23:44:31, Robert Hyatt wrote: >>>> >>>>>On October 03, 1999 at 23:17:29, Ricardo Gibert wrote: >>>>> >>>>>>[snip] >>>>>>> >>>>>>>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...' >>>>>>> >>>>>>>:) >>>>>> >>>>>>Ok, you got me. I neglected to explicitly state I was refering to the _chess_ >>>>>>version of the term. >>>>>> >>>>> >>>>> >>>>>then here is a 3-move sequence. Sacrifice or combination? >>>>> >>>>>RxB, NxR, RxN. >>>>> >>>>>RxB obviously dumps a rook for a knight. or if you look to the end of the >>>>>combination it wins two pieces for a rook which is a significant advantage. >>>>> >>>>>Sacrifice or combination? >>>>> >>>>>How is that different from QxP+, RxQ, RxR#?? >>>>> >>>>>Dumping a queen for a pawn? Or winning the king? >>>>> >>>>> >>>>>>> >>>>>>>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... >>>>>> >>>>>>You can give up a bishop to obtain a draw by perpetual check and because you >>>>>>never get the material back, it is a called a sacrifice. I know it seems trivial >>>>>>and is not what people generally have in mind when they use the term >>>>>>"sacrifice", but I do believe it's use in such cases is fairly universal. >>>>> >>>>> >>>>>in the case of a computer, it isn't 'sacrificing'. It _sees_ that it can >>>>>draw or that it can win. IE it isn't giving up _anything_. A human might >>>>>toss a bishop 'thinking' (but not sure) than he can force a perpetual. But >>>>>a computer either 'proves' that it can force it, or it won't ever go for the >>>>>move in the first place. IE we (as humans) gamble on things all the time. But >>>>>would it be the same as saying "I'll flip a coin and if it is heads I win, and >>>>>if it is tails you win" if I rig the coin so there is _no doubt_ that it will >>>>>end up heads when I want? >>>>> >>>>>That is the minor point here... computers don't sacrifice in the traditional >>>>>way usually. There are exceptions like the famous chaos sacrifice vs chess >>>>>4.x where chaos didn't see any materian coming back, but thought the position >>>>>justified the Nxe6 sac anyway... I see a number of those in Crafty. More than >>>>>I really want to see. But they do come close to the definition of a sacrifice >>>>>as nothing "real" is won back, just some intangible positional things that may >>>>>well not be enough to win with. >>>> >>>>Yes,even then, did chaos choose the move against a better move as related to its >>>> score,if it saw a move that left its score at +1.00 or the move it made at >>>> -1.00 did it go for the -1.00? I think a real sac in a computer is if it >>>>chosses a move against its score, or else it is still going on raw calculation. >>> >>>A serious human does not do sacrifices by your definition. >>>Sacrifice is the same as something that you believe that is clearly wrong by >>>your definition. >>> >>>Uri >>Not buy my definition, if you read the threads of which a true sacrafice is made >>then, A.there cant be material gain by it.B. there has to be a gamble. >>A computer program under this definition cant provide a "true" sacrafice >>because it would go against its evalution of the position,if it sees that it >>gives up a knight and the score still remains the same, it has not done a "true >>" sacrafice, if its score goes up it is not a true sacrafice either, my point is >>because of the logical functions of a computer program by the definition of >>"real" sac presented in the threads, then it is not possible (when it comes to a >>chess program) to give up material meaning taking a negative score in hopes that >>it may bring it to a + score in the long run. > >When humans give up material and hopes that it is going to bring them back in >the long run they use positional knoledge and evaluate the position after the >sacrifice as positive evaluation inspite of the fact that the opponent has >material advantage. > >They do not prefer position with negative score relative to positional with >positive score. > >Another case is when their evaluation of the position is based also on some >selective search and the selective search show positive score they are again may >have positive score and not negative score. > >In both cases it is a sacrifice by definition. > >Uri By definition of the threads on what a sac is and what one is not this can only mean that a program cannot make a real sac. My definiton of a sac is different than this. If a program sacs a peice say, for a pawn but its score has not gone down at all, it calculates it was a correct move (of course) then by the threads and the book article that was in the thread ,in their opinion would this be a sac? my opinion is yes? their difinition of a sac is what i am talking about.
This page took 0 seconds to execute
Last modified: Thu, 15 Apr 21 08:11:13 -0700
Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.