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Subject: Shredder 9 UCI has .pl2 memory problems

Author: William Penn

Date: 06:03:52 03/27/05


I believe that I have just had a new insight here. I've run hundreds of these
tests with different positions. It looks like .pl2 remembers prior analysis OK
when the best response involves a capture. Otherwise it forgets, or doesn't
access .pl2 properly.

For example:
The final position in a correspondence game was analyzed in infinite mode for
over 8 hours. The best continuation was found to be 35.Red2 Nc4 36.Bxc4 bxc4
with an evaluation of -0.04. So I sent my move 35.Red2 to opponent, and opponent
replied with 35...Nc4. That gave the following position:

6r1/1k1r1pp1/p1b1p2p/1p6/1PnB4/1BP2P2/P2R2PP/2KR4 w - -

Now, when reloading the game and starting analysis of this position, it
immediately remembers that the best continuation is 36.Bxc4 bxc4 and assigns the
-0.04 evaluation value obtained in the long 8+ hour analysis above. This is
obvious as it goes through the cycles to higher and higher ply levels in
infinite mode. The first move pair 36.Bxc4 bxc4 and the -0.04 evaluation is made
instantly as each new ply level begins its calculation. It only remembers the
best first move pair, so must recalculate all of the alternate move
possibilities, nevertheless it is saving a lot of time in this new analysis. The
prior 8+ hour analysis reached a level of 27/47 after 8+ hours. This new
analysis (in current progress) has achieved the 23/23 level in 5 minutes, the
24/24 level in 10 minutes, and the 25/25 level in 19 minutes. So it is saving a
lot of time.

Too bad that this only happens when a capture is involved, but not otherwise.
 :o(
The reason for this strange behavior is a big mystery still to be solved. I can
only guess, but suspect a coding error related to accessing the .pl2 file.
WP



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