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Subject: Re: Congratulations to Rebel Century

Author: Vincent Lejeune

Date: 09:29:11 10/05/99

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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

Human can make real sacrifice, eg : Kasparov had sacrifice many times one pawn
in early middle game to get an active position or everybody how had white
against Sicilian-Poisoned-Pawn do a sacrifice with 'vague' compensation.



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