Small speed-up in pawn.cpp
Results for 10 tests for each version:
Base Test Diff
Mean 1435636 1445238 -9602
StDev 22576 23189 1848
p-value: 1
speedup: 0.007
No functional change
Resolves#295
There's no reason to define it as a Bitboard, so for consistency, use bool.
This is even a speedup on my machine: i7-3770k, using gcc 4.9.1 (linux):
stat test master diff
mean 2,341,338 2,327,998 13,134
stdev 15,765 14,717 5,405
speedup 0.56%
P(speedup>0) 100.0%
No functional change.
Resolves#298
minKingPawnDistance is used only as local variable in one place so we don't need it to be part of "Pawns::Entry" structure.
No functional change.
Resolves#277
It is up to material (and pawn) table look up
code to know where the per-thread tables are,
so change API to reflect this.
Also some comment fixing while there
No functional change.
ShelterWeakness and Stormdanger array are now indexed additionally by
file pair (a/h,b/g,c/f,d/e). The special case of king blocking a pawn
is incorporated in the StormDanger array. Finally the 93 parameters
are tuned by SPSA on LTC.
STC
ELO: 3.46 +-2.2 (95%) LOS: 99.9%
Total: 40000 W: 8275 L: 7877 D: 23848
LTC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 10311 W: 1876 L: 1721 D: 6714
Bench: 9498821
Resolves#163
When evaluating double pawns we use always
lsb() to extract the frontmost square.
This breaks evaluation color symmetry as is
possible to verify with an instrumented evaluate()
Value evaluate(const Position& pos) {
Value v = do_evaluate<false>(pos);
Position p = pos;
p.flip();
assert(v == do_evaluate<false>(p));
return v;
}
Passed no regression test:
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 21035 W: 4244 L: 4122 D: 12669
LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 39839 W: 6662 L: 6572 D: 26605
bench: 8255966
Instead of hard-code the weights in a big table,
we prefer to calculate them out of few parameters
at startup. This allows to keep low the number of
independent parameters and hence is good for tuning
and for a better insight in the meaning of the numbers.
No functional change.
Make even more clear what are the terms that
contribute to evaluate connected pawns, and
completely separate them from the weights
that are now fully looked up in a table.
For future tuning makes sense to init the table with
a formula instead of hard-code it. This allows to
reduce problem space cardinality and makes tuning
easier.
And fix a MSVC warning while there:
warning C4804: '>>' : unsafe use of type 'bool' in operation
No functional change.
These two notions are very correlated. Since connected has the most
generality, it makes sense to generalize it to encompass what is
covered by candidate.
STC:
LLR: 4.03 (-2.94,2.94) [-3.00,1.00]
Total: 11970 W: 2577 L: 2379 D: 7014
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 13194 W: 2389 L: 2255 D: 8550
bench 7328585
Idea from Lyudmil Tsvetkov.
The value seems to be raised a bit abruptly, but as
Gary said, a blocked pawn on the sixth rank has been
instrumental in limiting king mobility in multiple
losses that I've seen from SF. A blocked pawn on fifth
rank is much less serious on the king safety impact.
Passed both STC
LLR: 2.97 (-2.94,2.94) [-1.50,4.50]
Total: 14551 W: 2750 L: 2607 D: 9194
and LTC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 43595 W: 6917 L: 6618 D: 30060
And even a retest at 60" fixed games 40K
ELO: 1.79 +-1.9 (95%) LOS: 97.0%
Total: 39889 W: 6018 L: 5813 D: 28058
bench: 7154916
Prefer
file_of(s) < file_of(ksq)
to the inidrect
file_of(ksq) < FILE_E
To evaluate if semiopen side to check is the left side.
Also other small touches while there.
No functional change.
We add a penalty for each pawn which is not protected by another pawn
of the same color.
Passed both short TC
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 12107 W: 2411 L: 2272 D: 7424
And long TC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 9204 W: 1605 L: 1458 D: 6141
bench: 7682173
This hacky rule allows to get an about right eval out of this position:
r2qk2r/ppp2p2/2npbn2/2b1p3/2P1P1P1/2NB1PPp/PPNP3K/R1BQ1R2 b kq - 0 13
And, more importantly, passed both short TC:
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 6239 W: 1249 L: 1127 D: 3863
And long TC:
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 38371 W: 6165 L: 5888 D: 26318
bench: 8183238
Stéphane Nicolet