Author: William Penn
Date: 13:31:51 12/01/00
Some observations re CM8000 user-defined personalities
Regarding a CM8000 Selective Search setting of 32 (obtained by editing the
appropriate byte in a personality file with a hex editor) versus the standard
Selective Search maximum setting of 12:
I used the equivalent of Shep's CM6666 and CM6666 Deep as the two personalities
for my comparison tests. For purposes of easy reference here, I'll dub them
CM8666 and CM8666 Deep. The CM8666 personality had Sel.Srch.=12. CM8666 Deep
had Sel.Srch.=32, but was otherwise identical to CM8666.
I used a typical middlegame position for my comparison tests, chosen partly
because it didn't take too long to get to higher ply calculations.
There was no difference in any Thinking Lines window information at 13 ply or
less. However there was a big difference in the time required to complete the
calculations at 14 ply. Apparently a Selective Search setting of 32 causes
certain moves to be discarded more quickly with CM8666 Deep when analysis
reaches the 14 ply level, and presumably beyond that level.
===========================================
CM8666 Deep (Sel.Srch.=32)
time depth score positions moves
10:00 13 -1.63 41072171 Rfd8...
28:37 14 -1.77 120083265 Rfd8...
1:01:20 15 -1.85 257767455 Rfd8...
2:54:15 16 -1.99 742496963 Rfd8...
===========================================
CM8666 (Sel.Srch.=12)
time depth score positions moves
9:47 13 -1.63 41072171 Rfd8...
27:44 14 -1.77 120082436 Rfd8...
2:25:54 15 -1.85 622084976 Rfd8...
------- 16 ----- --------- -------
===========================================
Most of the extra time required to reach the 15 ply level with CM8666 was spent
in evaluating moves at the 14 ply level. After all 14 ply moves had been
analyzed, it then took only about 22 minutes to analyze the first line at 15 ply
as shown in the table above. It would presumably take a long time to complete
the analysis to 16 ply with CM8666. So I aborted the CM8666 test after a total
of 4 hours and 37 minutes. At that point it had 28 moves left to analyze out of
43 total moves at the 15 ply level and had processed about 1,210,000,000
positions.
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Here are a couple of other observations regarding user-defined personalities:
Some tests with the CM8666 and CM8666 Deep personalities with certain positions
produced an unusual ordering of multiple evaluations within a certain ply in the
Thinking Lines window. For example if calculating at the 10 ply level with
black to move, the first line found and displayed may have a score of 0.50.
Then still at 10 ply with black to move, the second line found may have a value
of 0.75. That appears to be calculating in the wrong direction. Using the
standard protocol which I believe most people expect, calculations with black to
move should proceed to find smaller scores (not larger scores) at the same ply
level! That has been explained elsewhere as normal for the CM8000 Thinking
Lines window, and only the last move found should be considered correct, prior
moves being "outdated". But I wasn't entirely convinced, so I tried to isolate
the cause...
I tried all of the possible CM8000 personality setting changes, one by one.
Only changes in King Safety (a Positional setting) from the default of 100
caused the strange analysis data mentioned in the prior paragraph. Returning
that setting to the default of 100 removed/prevented such strange analysis data.
That's not conclusive and more tests are needed, but it suggests that there
could be a problem with changing the King Safety setting from the default of
100.
In performing these various tests, it also appears that changes in user-defined
personalities is not initialized automatically by CM8000. It is necessary to do
something special in order to refresh the system (such as load a stored game
containing that personality, or exit/reload CM8000, or restart the computer).
Otherwise the old personality settings may still be used in analysis.
These tests were run with a Celeron 500MHz processor, 192MB RAM, Windows 98se,
and the typical CM8000 installation.
WP
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