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Subject: Re: quiescent nodes, and history heuristic....

Author: Robert Hyatt

Date: 09:54:32 01/30/03

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On January 30, 2003 at 11:19:24, Russell Reagan wrote:

>On January 30, 2003 at 09:42:01, Andrew Williams wrote:
>
>>To illustrate why SEE is better than MVV/LVA, suppose you have a position where
>>White attacks two of black's minor pieces (worth 300 points each). In each case,
>>White has one attacker on the piece. One of these pieces is attacked by a Rook
>>and is not defended. The other is attacked by a Pawn but is defended. SEE will
>>tell you that the rook capture is better, because it will calculate a material
>>gain of 300 points versus a material gain of 200 points. MVV/LVA will tell you
>>that the Pawn capture is better, because the score will be (300-1) versus
>>(300-5) for the Rook capture. The difference is that if the rook capture would
>>give you a beta cutoff and the pawn capture wouldn't, you'll do a lot of
>>unnecessary work by searching them in the wrong order
>
>Thanks for your comments, and I have a question.
>
>Are both SEE and MVV/LVA only concerned with captures on a single square?

Yes.  MVV/LVA says "find the most valuable piece that I can capture, and then
capture it with the least valuable attacker that is attacking it.  That is on
_one_ square.
Just like a SEE sequence of exchanges on one square.  Yes, you look at all
squares with
MVV to find the most valuable victim.  But you do the same with SEE to find the
square you want to analyze exchanges on.


> I have
>always thought of MVV/LVA to be a kind of qsearch. I think some people have
>different definitions of what SEE is. For instance, I recall Vincent saying that
>you can just call SEE() + Eval() straigth from your search function instead of
>calling QSearch(), so he obviously sees it as a whole board thing instead of
>something on a single square. I have always thought it was a whole board thing
>also, but I have never implemented it.



You can do that.  A _very_ early version of "blitz" (my original chess program)
did that
in fact, and it played pretty well.  But it won't handle things like overloaded
pieces because
it limits the q-search to a single square, the square you moved to at the last
ply.

Someone has claimed that Junior does this, whether that is fact or urban legend
is another
issue...




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