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
We want all the UCI options are printed in the order in which are
assigned, so we use an index that, depending on Options.size(),
increases after each option is added to the map. The problem is
that, for instance, in the first assignment:
o["Write Debug Log"] = Option(false, on_logger);
Options.size() can value 0 or 1 according if the l-value (that
increments the size) has been evaluated after or before the
r-value (that uses the size value).
The culprit is that assignment operator in C++ is not a
sequence point:
http://en.wikipedia.org/wiki/Sequence_point
(Note: to be nitpick here we actually use std::map::operator=()
that being a function can evaluate its arguments in any order)
So there is no guarantee on what term is evaluated first and
behavior is undefined by standard in this case. The net result
is that in case r-value is evaluated after l-value the last
idx is not size() - 1, but size() and in the printing loop
we miss the last option!
Bug was there since ages but only recently has been exposed by
the removal of UCI_Analyze option so that the last one becomes
UCI_Chess960 and when it is missing engine cannot play anymore
Chess960.
The fix is trivial (although a bit hacky): just increase the
last loop index.
Reported by Eric Mullins that found it on an ARM and MIPS
platforms with gcc 4.7
No functional change.
Thanks to std::bitset we can easily increase
the limit of active threads above 64.
Thanks to Lucas Braesch for pointing at the
correct solution of using std::bitset.
No functional change.
Using memset on a std::vector is undefined behavior,
so manually init all the data memebers of LimitsType.
Bug intorduced in 41641e3b1e
No functional change.
Because we test for available slaves before
entering split(), we almost always allocate a
slave, only in the rare case of a race (less
then 2% of cases) this is not true, but to
special case this occurrence is not worth
the added complexity.
bench: 7451319
Split delta value in aspiration window so that when
search depth is less than 24 a smaller delta value
is used. The idea is that the search is likely to
be more accurate at lower depths and so we can exclude
more possibilities, 25% to be exact.
Passed STC
LLR: 2.96 (-2.94, 2.94) [-1.50, 4.50]
Total: 20430 W: 3775 L: 3618 D: 13037
And LTC
LLR: 2.96 (-2.94, 2.94) [0.00, 6.00]
Total: 5032 W: 839 L: 715 D: 3478
Bench: 7451319
During endgame initialization we get the material
hash key of each endgame forging and ad-hoc position
that in same cases is illegal (leaves teh king under
capture). This is not a problem for the material key,
but rises an assert when SF is run in debug mode with
'testKingCapture' set in pos_is_ok().
So rewrite the code to always produce legal positions.
No functional change.
Big simplification of pawn move check.
Code has been tested with a brute force approach: for
every position reached during a bench search, the function
has been called for each combinations of Move(from, to)
and verified the result is the same of old code.
Actually this function is very critical becuase is the
one that ensures corrupted TT moves are discarded, so
to properly test it a simple bench is not enough.
Verified also speed is not changed.
No functional chnage.
It has been obsoleted out already some time ago
and currently there is no point in changing eval
score according to if we are in game or analyzing.
So retire the option.
No functional change.
Try to avoid repetition draws at early midgame,
this should give an edge against weaker opponents
and reduce draw rate.
Tested for regressions with SPRT[-3, 1] and
passed both short TC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 68498 W: 12928 L: 12891 D: 42679
And long TC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 40212 W: 6386 L: 6295 D: 27531
bench: 7990513
When running the following position:
8/kPp5/2P3p1/p1P1p1P1/2PpPp2/3p1p2/3P1P2/5K2 w - - 0 1
An assert is raised at depth 92:
assert(-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE);
This is because it happens that beta = 29832,
so rbeta = 30032 that is > VALUE_INFINITE
Bug spotted and analyzed by Uri, fix suggested by Joerg.
Other fixes where possible but this one is pointed
exactly at the source of the bug, so it is the best
from a code documentation point of view.
bench: 8430785
Under some very rare case 100 plies of search
could be not enough. Increasing more could lead
to crashes due to reached stack size limit on
some platforms.
Strongly requested by Uri.
bench: 8430785
Currently king has no material key associated because
it can never happen to find a legal position without
both kings, so there is no need to keep track of it.
The consequence is that a position with only the two
kings has material key set at zero and if the material
hash table is empty any entry will match and this is
wrong.
Normally bug is hidden becuase the checking for a draw
with pos.is_draw() is done earlier than evaluate() call,
so that we never check in gameplay the material key of a
position with two kings.
Nevertheless the bug is there and can be reproduced setting
at startup a position with only two kings and typing
'eval' from prompt.
The fix is very simple: add a random key also for the king.
Also fixed the condition in material.cpp to avoid asserting
when a 'just 2 kings' postion is evaluated.
No functional change.
Actually MultiCut is too different from current scheme.
Note that neither ProbCut is exactly what we do because
we try just a handful of captures instead of all moves,
nevertheless it seems more in line with what we do.
Suggested by Joona.
No functional change.
