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Subject: Re: How to beat Rebel 9 in 16 moves!!

Author: Robert Hyatt

Date: 18:10:50 11/10/97

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On November 10, 1997 at 10:45:51, Randolph S. Baker wrote:

>On November 09, 1997 at 23:07:06, Robert Sherman wrote:
>
>>On November 09, 1997 at 18:00:30, Ed Schröder wrote:
>>
>>
>>>
>>>I am aware of this for years. Rebel is programmed for fast recaptures.
>>>This algorithm of course has some negative side effects shown in the
>>>below game which fortunately are big exceptions.
>>>
>>>Still I prefer to leave it the way it is now because removing the
>>>algorithm would mean Rebel will think 3-5 minutes again on simple
>>>recaptures. I received too many complaints about that in the past.
>>>
>>>Thus so now and then you are lucky :)
>>>
>>>- Ed Schroder -
>>>
>>>
>>
>>
>>I disagree that this is a "simple recapture."  In this game there is a
>>material imbalance and a positional imbalance.  The Nxc7 is a sacrifice
>
>Furthermore, a N giving itself up for a P in any position should warrant
>additional inspection. Surely anyone who volunteers material freely
>might be "up to something", and the time management algorithm should
>take this into account.


if you go back to a very famous game between Cray Blitz and Belle in
1981,
(the position in a couple of the test suites where white plays Bxh6 to
produce
a draw by repetition) and you back up a couple of moves, you find black
leaving
a knight hanging on b6.  Cray Blitz was running in a batch mode and was
getting
1 minute per move to account for gross delays we had to deal with.  This
was
one of those "that was easy" moves and it spent only 1/3 of it's normal
time
and decided the knight was hanging.  10 more seconds would have shown
that
it wasn't.  Bad thing was, back then, we were only searching about 3K
nodes
per second on a very early cray, and that wasn't enough to find the Qxb6
nearly
lost, and that a move later Bxh6 was the only way to salvage a draw.

needless to say I tightened up the definition of an "easy" move after
that
and have not been burned since, although on occasion I wish it would
move
easier.  IE after QxQ it can play PxQ and shred its pawn structure, or
NxQ
and not shred anything, but since there are two recapture moves that are
"close" it grinds on for the full time, always liking NxQ better...

But it is safe... :)





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