Author: Lanny DiBartolomeo
Date: 06:26:19 10/06/99
Go up one level in this thread
On October 06, 1999 at 08:49:41, blass uri wrote: >On October 06, 1999 at 01:17:57, Lanny DiBartolomeo wrote: > >>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. > >The score represents what the player believe about the result of the game. >The score is low only if you believe that you are going to lose. > >You cannot expect someone(human or program) to prefer a losing move. > >Uri Ok, I see what your saying, bare with me here :)), a chess program being only pure logic cannot make a true chess sac because a sac is based on "gut instinct" and a blend of course of the tangeable factors, a chess program would "see" but would not have the "feeling" based on different circumstances so it would look like it sacs by the threads definition but to a program it would have been thru correct calculation,kind of like you see a series of moves and you do it because you Know through pure calculation it is good for your game, when a sac is more on the lines you see something you do it because you feel it is the best move to produce a better game, it is based on the evidence and your feelings that you will obtain a better game though your not fully sure you gambled. This is what i mean by a comp taking a -score i dont mean because it is truly negative, it is the only way i could think of voiding out the raw calculation of a program and to prove the kind of instinct needed in the threads type of sac. Is there instinct Factors in a "true" sac?
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