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Subject: SEE & accuracy

Author: Stuart Cracraft

Date: 10:20:11 08/21/04


All,

SEE increases my nominal iteration depth by 0.42 pawns
given the same amount of time as a non-SEE search, all else

SEE decreases my max quiescence depth reached (with a check handoff
to main search) by a little under 8 ply for the same problem set.

These are the 300 positions from Win-at-Chess run at 1 second per
problem on an old, slow, notebook. I do not have comparative data
due to the subjectivity involved of chess games and the "feel of SEE".

Legend:
Ave Iterative Depth/Average Max Search depth
% solved
Total solved / Total in test
Total time taken (300 seconds allowed)
Total Nodes searched
Average positions searched per problem /
Average time (rounded) per problem /
Average nodes per second per problem
0/0/Check Extensions from Quiescence back to Main Search/0/0

Without SEE

**** 6.68/27.18 68% 204/300 269.05 54264704 180882/1/201692 0/0/3361112/0/0/0

With SEE

**** 7.10/19.01 64% 193/300 267.44 46135172 153784/1/172505 0/0/1154026/0/0/0

Total problem solution rate drops 5.4% and nodes searched drops 14.98%

(The SEE being used above was tried as (1) see < 0 then don't search
a capture move in quiescence and (2) see < delta where delta is calculated
with its margin off alpha as the maximum positional score so far in the
search for the side on move. The above results are the combination of both and
if only using the #2, assuming for example my SEE is not a great SEE,
the result is only slightly changed.)

My question is, why should SEE reduce the tactical result so drastically
and is it safe to do so given the depth and nodes results are favorable?

Thanks ahead,

Stuart



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