Stephane's patch removes the only usage of Position::see, where the
returned value isn't immediately compared with a value. So I replaced
this function by its optimised and more specific version see_ge. This
function also supersedes the function Position::see_sign.
bool Position::see_ge(Move m, Value v) const;
This function tests if the SEE of a move is greater or equal than a
given value. We use forward iteration on captures instread of backward
one, therefore we don't need the swapList array. Also we stop as soon
as we have enough information to obtain the result, avoiding unnecessary
calls to the min_attacker function.
Speed tests (Windows 7), 20 runs for each engine:
Test engine: mean 866648, st. dev. 5964
Base engine: mean 846751, st. dev. 22846
Speedup: 1.023
Speed test by Stephane Nicolet
Fishtest STC test:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 26040 W: 4675 L: 4442 D: 16923
http://tests.stockfishchess.org/tests/view/57f648990ebc59038170fa03
No functional change.
Drop useless condition
abs(ttValue) < VALUE_KNOWN_WIN
And extend singular extension search to cases when ttValue
stores a mate score. This improves mate finding and does
not introduce any regression.
Yery tested this patch against current master on the 6500+
Chest mate suite with 200K fixed nodes:
shortest mates found: master: 1206 patch:1205
any mate found: master: 1903 patch: 2003
with 1 sec time:
shortest mates found: master: 2667 patch: 2628
any mate found: master: 3585 patch: 3646
Verified for no regression:
STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 25655 W: 4578 L: 4465 D: 16612
LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 66247 W: 8618 L: 8557 D: 49072
bench: 6335042
Checking for legality of a possible ponder move
must be done before we undo the first pv move,
of course. (spotted by mohammed li.)
This obviously only has any effect when playing in ponder mode.
No functional change.
A middle ground patch of two successful tuning patches,
one at STC, the other at LTC, which now passed both.
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 67893 W: 12777 L: 12384 D: 42732
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 30165 W: 4189 L: 3960 D: 22016
bench: 9209507
Currently, helper threads will only search up to the
specified depth limit. Now let them search until the
main thread has finished the specified depth.
On the other hand, we don't want to pick a thread with
a higher search depth.
This may be considered cheating. ;-)
No functional change.
Both are the result of a SPSA tuning session with a custom book, 50k iterations each.
After an additional tuning session of the mobility values, tuning the delta values, with following result.
40k games at 9+0.05:
ELO: 4.13 +-2.2 (95%) LOS: 100.0%
Total: 40000 W: 8581 L: 8106 D: 23313
and LTC
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 36518 W: 6049 L: 5782 D: 24687
Bench: 8567402
Resolves#284
The eval already returns zero in KK, KBK, KNK (see material.cpp). The difference is:
- we lose the "TB pruning" benefit of the draw rule (ie. search goes on even if eval is zero)
- we gain some speed by removing a useless test from the hot path
STC:
LLR: 0.05 (-2.94,2.94) [-3.00,1.00]
Total: 128000 W: 21357 L: 21560 D: 85083
LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 33023 W: 4613 L: 4509 D: 23901
bench 7461881
With Eelco's patch "Don't special case for abs(beta) >= VALUE_MATE_IN_MAX_PLY" condition "abs(ttValue) < VALUE_KNOWN_WIN" has been removed from singular extension search, and condition "abs(beta) < VALUE_KNOWN_WIN" was added to the SingularExtensionNode definition.
This might lead to problems, especially in positions, where a mate is due.
For example, this position 5rk1/4K1pp/8/5PPP/8/8/8/1R6 w - - 12 1 triggers an assert.
stockfish: search.cpp:434: Value {anonymous}::search(Position&, Search::Stack*, Value, Value, Depth, bool) [with {anonymous}::NodeType NT = (<unnamed>::NodeType)2u; bool SpNode = false]: Assertion `-VALUE_INFINITE <= alpha && alpha < beta && beta <= VALUE_INFINITE' failed.
So let's re-insert the removed condition.
First spotted by Uri Blass, fix by me.
Bench: 8759675
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
Makes more sense than returning a draw score. Tested
with reduced MAX_PLY = 30 and passed both short TC
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 17434 W: 3345 L: 3194 D: 10895
And long TC
LLR: 2.97 (-2.94,2.94) [0.00,6.00]
Total: 2610 W: 488 L: 373 D: 1749
With current limit of MAX_PLY = 100 the patch should not
introduce any measurable change, nevertheless is the correct
approach.
Idea of returning eval is from Michel Van den Bergh.
bench: 8430785
Latest master triggers a compiler warning due
to comparing int64_t to uint64_t.
notation.cpp: In Funktion »std::string pretty_pv(Position&, int, Value, int64_t, Move*)«:
notation.cpp:230:30: Warnung: Vergleich zwischen vorzeichenbehafteten und vorzeichenlosen Ganzzahlausdrücken [-Wsign-compare]
This patch should fix it.
No functional change.
Use a skew-logistic function to replace the
MoveImportance[] array.
Verified it does not regress at fixed number
of games both at short TC:
LLR: -2.91 (-2.94,2.94) [-1.50,4.50]
Total: 39457 W: 7539 L: 7538 D: 24380
And long TC:
ELO: -0.49 +-1.9 (95%) LOS: 31.0%
Total: 39358 W: 6135 L: 6190 D: 27033
bench: 7335588
Actually, it is not used, as both arrays have the
same values. Some local tests in either direction
showed no improvement.
Also some minor corrections in the comments.
No functional change.
If the game got late enough that move_importance(currentPly) * slowMover / 100
rounds to 0, then we ended up dividing 0 by 0 when only looking 1 move ahead.
This apparently caused the search to almost immediately abort and Stockfish
would blunder in long games. So convert thisMoveImportance to a double.
No functional change.
This seems more a material imbalance topic,
anyhow test is good and so patch is applied
as is.
Passed both short TC:
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 17391 W: 3548 L: 3393 D: 10450
And long TC:
LLR: 3.00 (-2.94,2.94) [0.00,6.00]
Total: 34660 W: 5972 L: 5700 D: 22988
bench: 8291883
The init_eval() function corrupted the static array castleRightsMask[]
in the Position class, resulting in instant crashes in most Chess960
games. Fixed by repairing the damage directly after the function is
called. Also modified the Position::to_fen() function to display
castle rights correctly for Chess960 positions, and added sanity checks
for uncastled rook files in Position::is_ok().
