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

Author: Ed Schröder

Date: 15:00:30 11/09/97

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>Posted by Robert Sherman on November 09, 1997 at 12:37:35:

>This post is not meant to demean Rebel 9 in any way.  Rebel 9 is, in my
>opinion, a very strong program with many nice features that makes it a
>significant upgrade over Rebel 8.  Although Rebel 8 and Rebel 9 are very
> strong, I have uncovered a glitch in respect to the amount of time the
>programs spend on taking the piece on certain sacrifices.  The following
>game was played on a "obsolete Pentium 100", so it may not be applicable
> to the faster machines.  I did send this game to Ed Schroder when he
>was producing Rebel 9.  On a fixed level Rebel 9, does see the impending
>mate 15 seconds later then it does when playing at a 40/2 tournament
>level.  This may mean that Mr. Schroder was testing Rebel 9 on faster
>machines and didn't believe that the need to make changes to the way
>Rebel 9 allocates time would make any sense.  My belief is that when a
>sacrifice is played, the program should realize that move is very
>critical for the game and spend a long time analyzing whether the sac is
>sound or not.  Anyway, on the fixed time level, Rebel 9 finds a
>refutation the second fastest of programs I have tested, second only to
>Genius.  Also, shareware programs never reject taking the knight bait
>while taking deep searches.  While all commercial programs find the
>looming mate (except Rebel because of the timing glitch) and make the
>appropriate move.  So this game seems to separate the "men from the
>boys."  I have not tested this game on Crafty or some commercial
>programs (Hiarcs 6, CSTal, Shredder), so I would be interested to see
>how they do. Without further ado, here is the game: (Sorry I didn't have
>time to put it in PGN)

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 -



>White : Robert Sherman   Black: Rebel 9

>1. e4  e5   2. Nf3  Nc6   3. Bc4  Bc5   4. Nc3  Nc6  5. Nd5  Nxe4  6. d3
> Nxf2  7. Qe2  Nxh1  8. Ng5  O-O   9. Nxc7  Qxc7  10. Qh5  h6  11. Bxf7
>Kh8  12. Qg6  Qa5  13. c3  Qxc3  14. bc  Bf2  15. Kd1  Ne7  16. Qh7#




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