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2559 commits

Author SHA1 Message Date
FauziAkram
243f7b264a Improve grammar of comments 
closes https://github.com/official-stockfish/Stockfish/pull/4801

No functional change
 2023-09-29 22:18:17 +02:00
Stefan Geschwentner
154b8d3ecb Remove VALUE_KNOWN_WIN. 
After removing classic evaluation VALUE_KNOWN_WIN is not anymore returned explicit evaluation. So remove and replace it with VALUE_TB_WIN_IN_MAX_PLY.

Measurement on my big bench (bench 16 1 16 pos1000.fen) verifies that at least with current net the calculated evaluation lies always in the open interval  (-VALUE_KNOWN_WIN, VALUE_KNOWN_WIN).
So i consider this a non-functional change. But to be safe i tested this also at LTC as requested by Stephane Nicolet.

STC:
https://tests.stockfishchess.org/tests/view/64f9db40eaf01be8259a6ed5
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 455296 W: 115981 L: 116217 D: 223098
Ptnml(0-2): 1415, 50835, 123420, 50527, 1451

LTC:
https://tests.stockfishchess.org/tests/view/650bfd867ca0d3f7bbf25feb
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 35826 W: 9170 L: 8973 D: 17683
Ptnml(0-2): 12, 3523, 10645, 3722, 11

closes https://github.com/official-stockfish/Stockfish/pull/4792

Bench: 1603079
 2023-09-22 19:25:57 +02:00
cj5716
fce4cc1829 Make casting styles consistent 
Make casting styles consistent with the rest of the code.

closes https://github.com/official-stockfish/Stockfish/pull/4793

No functional change
 2023-09-22 19:14:29 +02:00
peregrineshahin
0e32287af4 Reorder some lines 
Now that qsearch has its own repetition detection we can flip the order of lines and remove the guard of depth < 0 which is not needed after reordering (i.e. it was there to prevent checking repetition again at depth ==0).

Passed STC:
https://tests.stockfishchess.org/tests/view/6502ecbb2cd016da89abc3fb
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 69536 W: 17668 L: 17490 D: 34378
Ptnml(0-2): 190, 7652, 18929, 7784, 213

Passed LTC:
https://tests.stockfishchess.org/tests/view/6505ce9072620bc881ea9086
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 52116 W: 13294 L: 13113 D: 25709
Ptnml(0-2): 26, 5176, 15471, 5361, 24

closes https://github.com/official-stockfish/Stockfish/pull/4791

No functional change
 2023-09-22 19:02:18 +02:00
Stéphane Nicolet
3f7fb5ac1d Reformat some comments 
Also include the bench to make Continuation Integration happy on Github.

Bench: 1603079
 2023-09-11 23:19:06 +02:00
Michael Chaly
ef22829616 Do more futility pruning in qsearch 
This patch introduces a third futility pruning heuristic in qsearch. The idea is
that the static exchange evaluation is much worse than the difference between
futility base and alpha. Thus we can assume that the probability of the move
being good enough to beat alpha is low so it can be pruned.

Passed STC:
https://tests.stockfishchess.org/tests/view/64fc982a5dab775b5359dc83
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 36576 W: 9484 L: 9170 D: 17922
Ptnml(0-2): 121, 4119, 9495, 4431, 122

Passed LTC:
https://tests.stockfishchess.org/tests/view/64fcc7935dab775b5359e1a9
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 135408 W: 34556 L: 34041 D: 66811
Ptnml(0-2): 56, 14462, 38165, 14953, 68

closes https://github.com/official-stockfish/Stockfish/pull/4781

Bench: 1330793
 2023-09-11 22:36:26 +02:00
cj5716
6d85f43e26 Simplify cutnode depth condition 
With this patch, the depth condition for the cutnodes reduction is loosened from
tte->depth() >= depth + 3 to just tte->depth() >= depth.

Passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 101152 W: 25830 L: 25682 D: 49640
Ptnml(0-2): 312, 11788, 26258, 11876, 342
https://tests.stockfishchess.org/tests/view/64fd15635dab775b5359eaa6

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 82542 W: 20980 L: 20824 D: 40738
Ptnml(0-2): 42, 8795, 23440, 8953, 41
https://tests.stockfishchess.org/tests/view/64fda3545dab775b5359fbf1

closes https://github.com/official-stockfish/Stockfish/pull/4780

Bench: 1479029
 2023-09-11 22:30:57 +02:00
FauziAkram
adf29b3fd6 Rename one variable 
To enhance code clarity and prevent potential confusion with the
'r' variable assigned to reduction later in the code, this pull
request renames it to 'reductionScale' when we use the same name
in the reduction() function.

Using distinct variable names for separate functions improves code
readability and maintainability.

closes https://github.com/official-stockfish/Stockfish/pull/4765

No functional change
 2023-09-03 09:10:27 +02:00
Disservin
3c0e86a91e Cleanup includes 
Reorder a few includes, include "position.h" where it was previously missing
and apply include-what-you-use suggestions. Also make the order of the includes
consistent, in the following way:

1. Related header (for .cpp files)
2. A blank line
3. C/C++ headers
4. A blank line
5. All other header files

closes https://github.com/official-stockfish/Stockfish/pull/4763
fixes https://github.com/official-stockfish/Stockfish/issues/4707

No functional change
 2023-09-03 08:24:51 +02:00
ttruscott
8cd5cbf693 Omit two unneeded tests 
These redundant tests were intended as a speed-up, but they do not seem
to provide any speed anymore.

STC: https://tests.stockfishchess.org/tests/view/64e9079c85e3e95030fd8259
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 134688 W: 34338 L: 34226 D: 66124
Ptnml(0-2): 426, 15122, 36124, 15258, 414

closes https://github.com/official-stockfish/Stockfish/pull/4767

No functional change
 2023-09-03 08:07:59 +02:00
Shahin M. Shahin
440feecb4d Reduce repetitions branches 
Increase reduction on retrying a move we just retreated that falls in a repetition:
if current move can be the same move from previous previous turn then we retreated
that move on the previous turn, this patch increases reduction if retrying that move
results in a repetition.

How to continue from there? Maybe we some variants of this idea could bring Elo too
(only testing the destination square, or triangulations, etc.)

Passed STC:
https://tests.stockfishchess.org/tests/view/64e1aede883cbb7cbd9ad976
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 424000 W: 108675 L: 107809 D: 207516
Ptnml(0-2): 1296, 47350, 113896, 48108, 1350

Passed LTC:
https://tests.stockfishchess.org/tests/view/64e32d629970091252666872
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 89682 W: 22976 L: 22569 D: 44137
Ptnml(0-2): 39, 8843, 26675, 9240, 44

closes https://github.com/official-stockfish/Stockfish/pull/4757

bench: 1574347
 2023-08-22 11:32:51 +02:00
cj5716
030b87182a Do more full window searches 
Remove the value < beta condition for doing full window searches.
As an added bonus the condition for full-window search is now much
more similar to other fail-soft engines.

Passed STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 244608 W: 62286 L: 62294 D: 120028
Ptnml(0-2): 758, 28772, 63214, 28840, 720
https://tests.stockfishchess.org/tests/view/64d72d365b17f7c21c0e6675

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 311460 W: 78909 L: 78985 D: 153566
Ptnml(0-2): 129, 33959, 87656, 33831, 155
https://tests.stockfishchess.org/tests/view/64dca2265b17f7c21c0ee06c

closes https://github.com/official-stockfish/Stockfish/pull/4755

Bench: 1624221
 2023-08-22 11:22:15 +02:00
Muzhen Gaming
fe0dca12f1 Simplify PvNode Reduction 
Remove the depth condition for PvNode reduction.

Simplification STC:
https://tests.stockfishchess.org/tests/view/64d308fa5b17f7c21c0e0303
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 38976 W: 10106 L: 9889 D: 18981
Ptnml(0-2): 129, 4479, 10040, 4726, 114

Simplification LTC:
https://tests.stockfishchess.org/tests/view/64d457db5b17f7c21c0e236f
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 156402 W: 39727 L: 39645 D: 77030
Ptnml(0-2): 71, 17143, 43696, 17215, 76

closes https://github.com/official-stockfish/Stockfish/pull/4747

Bench: 1493904
 2023-08-16 21:24:58 +02:00
Shahin M. Shahin
3322349c1a Simplify pieceValue to one phase. 
Simplifies the usage of pieceValues to mg values with the exception of pawnValues, After the removal of PSQT.

passed STC:
https://tests.stockfishchess.org/tests/view/64d147845b17f7c21c0dd86c
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 197248 W: 50168 L: 50125 D: 96955
Ptnml(0-2): 651, 23029, 51222, 23070, 652

passed LTC:
https://tests.stockfishchess.org/tests/view/64d212de5b17f7c21c0debbb
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 181170 W: 45949 L: 45893 D: 89328
Ptnml(0-2): 84, 19656, 51052, 19706, 87

closes https://github.com/official-stockfish/Stockfish/pull/4734

Bench: 1494401
 2023-08-13 11:58:08 +02:00
Stéphane Nicolet
495852fecd Simplify SEE pruning for captures 
It seems that the current search is smart enough to allow us to remove
(again) the block of code that checks for discovered attacks after the
first pruning condition for captures.

STC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 278848 W: 70856 L: 70903 D: 137089
Ptnml(0-2): 960, 32829, 71894, 32780, 961
https://tests.stockfishchess.org/tests/view/64d0af095b17f7c21c0dc440

LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 100704 W: 25564 L: 25425 D: 49715
Ptnml(0-2): 56, 10858, 28381, 11005, 52
https://tests.stockfishchess.org/tests/view/64d293e85b17f7c21c0df844

closes https://github.com/official-stockfish/Stockfish/pull/4736

Bench: 1470572
 2023-08-13 11:52:47 +02:00
FauziAkram
c02ee70927 Simplify prior countermove bonus 
Swapping a multiplication operation between two terms with a simple constant

Passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 60512 W: 15424 L: 15231 D: 29857
Ptnml(0-2): 200, 6985, 15712, 7140, 219
https://tests.stockfishchess.org/tests/view/64d2addf5b17f7c21c0dfae6

Passed LTC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 108456 W: 27545 L: 27414 D: 53497
Ptnml(0-2): 63, 11629, 30698, 11790, 48
https://tests.stockfishchess.org/tests/view/64d3ab6e5b17f7c21c0e1188

closes https://github.com/official-stockfish/Stockfish/pull/4738

Bench: 1636213
 2023-08-13 11:48:32 +02:00
Shahin M. Shahin
b7b7a3f3fa Detect repetitions before they happen in qsearch 
Passed STC:
https://tests.stockfishchess.org/tests/view/64d495995b17f7c21c0e29ed
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 340288 W: 86664 L: 85910 D: 167714
Ptnml(0-2): 1030, 38855, 89697, 39455, 1107

Passed LTC:
https://tests.stockfishchess.org/tests/view/64d5e1085b17f7c21c0e4ab5
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 193230 W: 49235 L: 48606 D: 95389
Ptnml(0-2): 98, 20432, 54921, 21071, 93

closes https://github.com/official-stockfish/Stockfish/pull/4742

Bench: 1579576
 2023-08-13 11:44:17 +02:00
cj5716
222f3ea55b Simplify a depth condition 
As the negative extension term has sensitive scaling, it would make more sense to allow more negative extension also at lower depth, and not just a region between low and high depth.

Passed STC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 124096 W: 31611 L: 31485 D: 61000
Ptnml(0-2): 422, 14437, 32205, 14561, 423
https://tests.stockfishchess.org/tests/view/64d205d75b17f7c21c0dea82

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 387882 W: 97840 L: 97993 D: 192049
Ptnml(0-2): 198, 42004, 109668, 41895, 176
https://tests.stockfishchess.org/tests/view/64d333f85b17f7c21c0e06c6

closes https://github.com/official-stockfish/Stockfish/pull/4743

Bench: 1542357
 2023-08-13 11:40:35 +02:00
Michael Chaly
d97a02ea2b Give extra bonus to main history for moves that caused a fail low. #4744 
Current master gives this type of bonuses to continuation history, this patch also gives them to main history.

Passed STC:
https://tests.stockfishchess.org/tests/view/64d4802a5b17f7c21c0e27b3
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 480768 W: 122767 L: 121798 D: 236203
Ptnml(0-2): 1563, 56190, 123834, 57309, 1488

Passed LTC:
https://tests.stockfishchess.org/tests/view/64d7e4c05b17f7c21c0e7456
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 32052 W: 8329 L: 8022 D: 15701
Ptnml(0-2): 19, 3335, 9015, 3634, 23

closes https://github.com/official-stockfish/Stockfish/pull/4744

Bench: 1711793
 2023-08-13 11:38:24 +02:00
Michael Chaly
5c2111cc30 Adjust futility pruning base in qsearch 
Current master used value from transposition table there if it existed,
this patch uses minimum between this tt value and the static eval instead
(this thus is closer to the main search function, which uses the static eval).

Passed STC:
https://tests.stockfishchess.org/tests/view/64cd57285b17f7c21c0d6a8c
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 252544 W: 64671 L: 64039 D: 123834
Ptnml(0-2): 839, 29207, 65575, 29785, 866

Passed LTC:
https://tests.stockfishchess.org/tests/view/64cf6c915b17f7c21c0d9fcb
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 60150 W: 15374 L: 15012 D: 29764
Ptnml(0-2): 24, 6321, 17024, 6681, 25

closes https://github.com/official-stockfish/Stockfish/pull/4725

Bench: 1573024
 2023-08-07 07:24:11 +02:00
FauziAkram
a26f8d37e1 Tweak formula for pruning moves losing material 
Simplify the "Prune moves with negative SEE" formula,
by removing one multiplication and subtraction operation.

Passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 214272 W: 54596 L: 54572 D: 105104
Ptnml(0-2): 741, 25160, 55320, 25164, 751
https://tests.stockfishchess.org/tests/view/64c430d1dc56e1650abbdbf6

Passed LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 238380 W: 60600 L: 60601 D: 117179
Ptnml(0-2): 132, 26069, 66791, 26064, 134
https://tests.stockfishchess.org/tests/view/64c81f155b17f7c21c0cee2b

closes https://github.com/official-stockfish/Stockfish/pull/4721

bench: 1655337
 2023-08-06 22:25:58 +02:00
Stéphane Nicolet
f84eb1f3ef Improve some comments 
- clarify the examples for the bench command
- typo  in search.cpp

closes https://github.com/official-stockfish/Stockfish/pull/4710

No functional change
 2023-07-28 23:38:49 +02:00
FauziAkram
2667316ffc Simplify one multicut extension 
Simplify away the ttValue <= alpha extension in the multicut block.

Passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 318336 W: 81307 L: 81398 D: 155631
Ptnml(0-2): 1088, 37291, 82469, 37264, 1056
https://tests.stockfishchess.org/tests/view/64b8589fdc56e1650abad61d

Passed LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 89388 W: 22925 L: 22775 D: 43688
Ptnml(0-2): 34, 9635, 25210, 9777, 38
https://tests.stockfishchess.org/tests/view/64bc41d0dc56e1650abb29cb

closes https://github.com/official-stockfish/Stockfish/pull/4709

bench: 1604592
 2023-07-25 16:43:35 +02:00
Stefan Geschwentner
76e1e8fd39 Simplify TT cutoff 
Remove the exact bound condition from TT depth check.

STC:
https://tests.stockfishchess.org/tests/view/64b30b320cdec37b957359e9
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 332928 W: 84895 L: 85003 D: 163030
Ptnml(0-2): 1242, 39200, 85604, 39260, 1158

LTC:
https://tests.stockfishchess.org/tests/view/64b74e2adc56e1650abac0b6
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 92946 W: 23628 L: 23482 D: 45836
Ptnml(0-2): 38, 10033, 26192, 10165, 45

closes https://github.com/official-stockfish/Stockfish/pull/4702

Bench: 1601764
 2023-07-24 02:23:43 +02:00
windfishballad
78e3d2ad78 Simplify some qsearch conditions 
Use the assert which ensures that beta == alpha+1 at PVNodes
to simplify a little bit the conditions further down in the code.

passed STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 56160 W: 14370 L: 14173 D: 27617
Ptnml(0-2): 210, 6192, 15076, 6395, 207
https://tests.stockfishchess.org/tests/view/64bc769cdc56e1650abb2e26

closes https://tests.stockfishchess.org/tests/view/64bc769cdc56e1650abb2e26

No functional change
 2023-07-24 02:09:44 +02:00
Joost VandeVondele
4b2979760f Check clock more often 
This patch changes the frequency with which the time is checked, changing
frequency from every 1024 counted nodes to every 512 counted nodes. The
master value was tuned for the old classical eval, the patch takes the
roughly 2x slowdown in nps with SFNNUEv7 into account. This could reduce
a bit the losses on time on fishtest, but they are probably unrelated.

passed STC:
https://tests.stockfishchess.org/tests/view/64bb8ae5dc56e1650abb1b11
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 76576 W: 19677 L: 19501 D: 37398
Ptnml(0-2): 274, 8592, 20396, 8736, 290

closes https://github.com/official-stockfish/Stockfish/pull/4704

No functional change
 2023-07-24 01:56:20 +02:00
Michael Chaly
5ea1cbc778 Do more futility pruning for cutNodes that are not in TT 
This is somewhat similar to IIR for cutnodes but instead of reducing
depth for cutnodes that don't have tt move we reduce margin multiplier
in futility pruning for cutnodes that are not in TT.

Passed STC:
https://tests.stockfishchess.org/tests/view/64b244b90cdec37b95734c5b
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 75552 W: 19404 L: 19029 D: 37119
Ptnml(0-2): 233, 8806, 19378, 9071, 288

Passed LTC:
https://tests.stockfishchess.org/tests/view/64b3ae5a0cdec37b95736516
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 104988 W: 27152 L: 26697 D: 51139
Ptnml(0-2): 41, 11259, 29446, 11700, 48

closes https://github.com/official-stockfish/Stockfish/pull/4700

bench 1727577
 2023-07-19 21:40:38 +02:00
Michael Chaly
913574f421 Remove improvement variable 
No longer used in a meaningful way.
Improve comments.

Closes https://github.com/official-stockfish/Stockfish/pull/4688

No functional change
 2023-07-16 15:18:41 +02:00
FauziAkram
acdbf45171 Use more expressive names for bonus1 and bonus2 
closes https://github.com/official-stockfish/Stockfish/pull/4683

No functional change
 2023-07-15 09:13:02 +02:00
Muzhen Gaming
6a8767a0d5 Simplify PvNode reduction 
Simplification STC: https://tests.stockfishchess.org/tests/view/64a415803ee09aa549c539c3
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 37856 W: 9719 L: 9504 D: 18633
Ptnml(0-2): 98, 4277, 9977, 4464, 112

Simplification LTC: https://tests.stockfishchess.org/tests/view/64a5ffe202cd07745c60f360
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 55878 W: 14323 L: 14138 D: 27417
Ptnml(0-2): 21, 5993, 15732, 6166, 27

closes https://github.com/official-stockfish/Stockfish/pull/4673

Bench: 2604965
 2023-07-11 22:55:00 +02:00
FauziAkram
9cd563cb54 Improving grammar and readability of comments 
closes https://github.com/official-stockfish/Stockfish/pull/4643

No functional change
 2023-07-03 18:38:41 +02:00
Muzhen Gaming
5f8480a730 Simplify score improvement reduction 
Reduce depth by 2 based on score improvement, only for depths 3 to 11.

Simplification STC: https://tests.stockfishchess.org/tests/view/64929a53dc7002ce609c7807
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 238912 W: 63466 L: 63468 D: 111978
Ptnml(0-2): 564, 26262, 65805, 26262, 563

Simplification LTC: https://tests.stockfishchess.org/tests/view/64942e47dc7002ce609c9e07
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 64452 W: 17485 L: 17320 D: 29647
Ptnml(0-2): 19, 6161, 19706, 6316, 24

closes https://github.com/official-stockfish/Stockfish/pull/4637

Bench: 2740142
 2023-07-03 18:33:27 +02:00
Muzhen Gaming
eb9aaf9489 Simplify away improvement term in null move search 
passed STC:
https://tests.stockfishchess.org/tests/view/649c0d2edc7002ce609d33b5
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 271104 W: 72181 L: 72217 D: 126706
Ptnml(0-2): 691, 30042, 74129, 29992, 698

passed LTC:
https://tests.stockfishchess.org/tests/view/649d0dd7dc7002ce609d4efa
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 183120 W: 49469 L: 49418 D: 84233
Ptnml(0-2): 84, 17636, 56063, 17699, 78

closes https://github.com/official-stockfish/Stockfish/pull/4650

Bench: 2642851
 2023-07-03 18:27:33 +02:00
peregrineshahin
fa143922ae Fix pruning to (in TB loss) in Null move pruning. 
Current logic can apply Null move pruning
on a dead-lost position returning an unproven loss
(i.e. in TB loss score or mated in losing score) on nonPv nodes.

on a default bench, this can be observed by adding this debugging line:
```
if (nullValue >= beta)
{
    // Do not return unproven mate or TB scores
    nullValue = std::min(nullValue, VALUE_TB_WIN_IN_MAX_PLY-1);
    dbg_hit_on(nullValue <= VALUE_TB_LOSS_IN_MAX_PLY); // Hit #0: Total 73983 Hits 1 Hit Rate (%) 0.00135166
    if (thisThread->nmpMinPly || depth < 14)
        return nullValue;
```

This fixes this very rare issue (happens at ~0.00135166% of the time) by
eliminating the need to try Null Move Pruning with dead-lost positions
and leaving it to be determined by a normal searching flow.

The previous try to fix was not as safe enough because it was capping
the returned value to (out of TB range) thus reviving the dead-lost position
based on an artificial clamp (i.e. the in TB score/mate score can be lost on that nonPv node):
https://tests.stockfishchess.org/tests/view/649756d5dc7002ce609cd794

Final fix:
Passed STC:
https://tests.stockfishchess.org/tests/view/649a5446dc7002ce609d1049
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 577280 W: 153613 L: 153965 D: 269702
Ptnml(0-2): 1320, 60594, 165190, 60190, 1346

Passed LTC:
https://tests.stockfishchess.org/tests/view/649cd048dc7002ce609d4801
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 246432 W: 66769 L: 66778 D: 112885
Ptnml(0-2): 83, 22105, 78847, 22100, 81

closes https://github.com/official-stockfish/Stockfish/pull/4649

Bench: 2425978
 2023-07-03 18:24:41 +02:00
cj5716
e551964ef6 Negative extension on cutNodes based on depth 
This patch was inspired by candirufish original attempt at negative extensions
here that failed yellow: https://tests.stockfishchess.org/tests/view/6486529065ffe077ca124f32

I tested some variations of the idea and tuned a depth condition for
a modified version of it here https://tests.stockfishchess.org/tests/view/648db80a91c58631ce31fe00
after noticing abnormal scaling (ie many passed STC but not LTC)
After some small tweaks I got the final version here

Passed STC:
LLR: 2.98 (-2.94,2.94) <0.00,2.00>
Total: 122208 W: 32776 L: 32350 D: 57082
Ptnml(0-2): 310, 13250, 33553, 13686, 305
https://tests.stockfishchess.org/tests/view/64997934dc7002ce609d01e3

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 145092 W: 39617 L: 39115 D: 66360
Ptnml(0-2): 54, 13691, 44552, 14197, 52
https://tests.stockfishchess.org/tests/view/649a1c5ddc7002ce609d0bff

closes https://github.com/official-stockfish/Stockfish/pull/4644

Bench: 2637784
 2023-07-01 13:06:49 +02:00
peregrineshahin
48f7c74f15 Fix Potential in TB cutoffs for NMP. 
Removes the second dependency on beta and caps the return value to VALUE_TB_WIN_IN_MAX_PLY - 1

Earlier tests:

STC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 193632 W: 51372 L: 51326 D: 90934
Ptnml(0-2): 447, 20111, 55687, 20091, 480
https://tests.stockfishchess.org/tests/view/6486ee4465ffe077ca125bc1

LTC:
LLR: 2.97 (-2.94,2.94) <-1.75,0.25>
Total: 331758 W: 89538 L: 89624 D: 152596
Ptnml(0-2): 114, 30121, 105516, 29993, 135
https://tests.stockfishchess.org/tests/view/6489401af42a44347ed7be42

updated constant:
LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 100260 W: 27143 L: 27017 D: 46100
Ptnml(0-2): 34, 8842, 32248, 8976, 30
https://tests.stockfishchess.org/tests/view/6492fcafdc7002ce609c818c

closes: https://github.com/official-stockfish/Stockfish/pull/4632
fixes: https://github.com/official-stockfish/Stockfish/issues/4598

bench: 2370027
 2023-06-22 10:26:17 +02:00
Joerg Oster
6eaa1c3ecd Fix indentation in qsearch. 
https://github.com/official-stockfish/Stockfish/pull/4630

No functional change.
 2023-06-20 10:47:07 +02:00
cj5716
0187546275 Small cleanup 
This non-functional change keeps formatting consistent.

closes https://github.com/official-stockfish/Stockfish/pull/4623

Bench 2370027
 2023-06-16 19:14:58 +02:00
Viren6
887bbd8b3d Remove setting of static to none if in check in qsearch 
Small simplification

Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/6487924d713491385c8034ae
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 59616 W: 15885 L: 15703 D: 28028
Ptnml(0-2): 144, 6130, 17086, 6296, 152

closes https://github.com/official-stockfish/Stockfish/pull/4618

No functional change.
 2023-06-14 18:33:56 +02:00
Stéphane Nicolet
92c949e12e Clean-up code indentation in qsearch 
closes https://github.com/official-stockfish/Stockfish/pull/4615

No functional change
 2023-06-13 08:42:55 +02:00
Michael Chaly
ece90bca9c Improve comments 
Fix comments for IIR, also document non-linear scaling in extensions.
Also add explicitly the bench, to fix an issue after the last commit.

closes https://github.com/official-stockfish/Stockfish/pull/4614

bench 2370027
 2023-06-12 21:17:31 +02:00
Guenther Demetz
e1dd005583 Reintroduce SEE verification against discovered attacks 
Reintroduces https://github.com/official-stockfish/Stockfish/pull/4453
along with https://github.com/official-stockfish/Stockfish/pull/4469

Leaving out
https://github.com/official-stockfish/Stockfish/pull/4533
https://github.com/official-stockfish/Stockfish/pull/4572

Passed STC:
https://tests.stockfishchess.org/tests/view/647d8c37726f6b400e408a0a
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 143168 W: 38346 L: 37892 D: 66930
Ptnml(0-2): 352, 15672, 39164, 15962, 434

Passed LTC:
https://tests.stockfishchess.org/tests/view/647ee8c528c4431bcb58e432
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 71538 W: 19560 L: 19190 D: 32788
Ptnml(0-2): 49, 6905, 21499, 7259, 57

closes https://github.com/official-stockfish/Stockfish/pull/4609

bench: 2595430
 2023-06-11 15:13:57 +02:00
cj5716
a9a6915e08 Simplify multiplier for improvement 
This simplifies a `* 99 / 1300` term into just `/ 13`.

Passed non-regression STC:
LLR: 2.92 (-2.94,2.94) <-1.75,0.25>
Total: 58816 W: 15727 L: 15540 D: 27549
Ptnml(0-2): 149, 6370, 16203, 6517, 169
https://tests.stockfishchess.org/tests/view/647d25e4726f6b400e408165

Passed non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 154386 W: 41749 L: 41669 D: 70968
Ptnml(0-2): 94, 14992, 46956, 15042, 109
https://tests.stockfishchess.org/tests/view/647d9b3c726f6b400e408b2a

closes https://github.com/official-stockfish/Stockfish/pull/4608

Bench:  2511327
 2023-06-11 15:05:54 +02:00
peregrineshahin
b60738e01b Fix no previous moves on root. 
guards against no previous move existing if qSearch is called on the root node (i.e. when razoring).

Passed Non-regression STC:
https://tests.stockfishchess.org/tests/view/647d242d726f6b400e408143
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 53120 W: 14167 L: 13976 D: 24977
Ptnml(0-2): 109, 5597, 14981, 5740, 133

closes https://github.com/official-stockfish/Stockfish/pull/4604

Bench: 2551691
 2023-06-06 21:07:43 +02:00
Michael Chaly
8dea070538 Move internal iterative reduction before probcut 
This patch moves IIR before probcut which allows probcut
to be produced at lower depths. Comments in IIR are also slightly updated.

Passed STC:
https://tests.stockfishchess.org/tests/view/6472d604d29264e4cfa749fd
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 387616 W: 103295 L: 102498 D: 181823
Ptnml(0-2): 976, 42322, 106381, 43187, 942

Passed LTC:
https://tests.stockfishchess.org/tests/view/6475eb8c4a36543c4c9f42e8
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 202836 W: 54901 L: 54281 D: 93654
Ptnml(0-2): 85, 19609, 61422, 20205, 97

closes https://github.com/official-stockfish/Stockfish/pull/4597

bench 2551691
 2023-06-04 23:12:23 +02:00
Linmiao Xu
ced0311890 Remove static eval threshold for extensions when giving check 
Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/647685d54a36543c4c9f4f2a
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 114688 W: 30701 L: 30571 D: 53416
Ptnml(0-2): 336, 12708, 31136, 12818, 346

Passed non-regression LTC:
https://tests.stockfishchess.org/tests/view/64774b02b81f005b572de770
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 107310 W: 28920 L: 28796 D: 49594
Ptnml(0-2): 33, 10427, 32621, 10531, 43

closes https://github.com/official-stockfish/Stockfish/pull/4599

bench 2597974
 2023-06-04 23:05:28 +02:00
Guenther Demetz
5930c0defb Simplify away SEE verification 
After 4 simplificatons over PR#4453 the idea does not yield significant
improvement anymore. Maybe also
https://tests.stockfishchess.org/tests/view/640c88092644b62c3394c1c5 was
a fluke.

Passed non-regression bounds:

STC:
https://tests.stockfishchess.org/tests/view/64705389c079b6583146d873
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 131936 W: 35040 L: 34930 D: 61966
Ptnml(0-2): 336, 14559, 36035, 14735, 303

LTC:
https://tests.stockfishchess.org/tests/view/6471a2ade549d9cf2fb213cd
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 407700 W: 109999 L: 110164 D: 187537
Ptnml(0-2): 279, 39913, 123689, 39632, 337

closes https://github.com/official-stockfish/Stockfish/pull/4595

bench: 2675974
 2023-06-04 23:01:14 +02:00
Muzhen Gaming
06186b786e Search tuning at very long time control with new net 
The most significant change would be the singularBeta formula.
It was first tested by cj5716 (see https://tests.stockfishchess.org/tests/view/647317c9d29264e4cfa74ec7),
and I took much inspiration from that idea.

LTC (fixed games): https://tests.stockfishchess.org/tests/view/6479d8da54dd118e1d990b12
Elo: 0.61 ± 1.2 (95%) LOS: 83.4%
Total: 60000 W: 16278 L: 16172 D: 27550
Ptnml(0-2): 16, 5845, 18179, 5937, 23
nElo: 1.38 ± 2.8 (95%) PairsRatio: 1.02

VLTC 180+1.8: https://tests.stockfishchess.org/tests/view/6479da1454dd118e1d990b2b
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 33224 W: 9261 L: 8984 D: 14979
Ptnml(0-2): 5, 2809, 10710, 3080, 8

SMP VLTC 8-thread: https://tests.stockfishchess.org/tests/view/647b0fe354dd118e1d992425
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 61398 W: 17386 L: 17081 D: 26931
Ptnml(0-2): 7, 4571, 21232, 4888, 1

closes https://github.com/official-stockfish/Stockfish/pull/4603

Bench: 2805878
 2023-06-04 22:54:13 +02:00
Michael Chaly
d99942f254 Small simplification for probcut in check 
Remove depth condition from there as not longer needed.

Passed STC:
https://tests.stockfishchess.org/tests/view/647367cad29264e4cfa753e6
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 254336 W: 67830 L: 67847 D: 118659
Ptnml(0-2): 580, 28181, 69697, 28096, 614

Passed LTC:
https://tests.stockfishchess.org/tests/view/647576184a36543c4c9f3af7
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 80706 W: 22048 L: 21898 D: 36760
Ptnml(0-2): 28, 7721, 24712, 7857, 35

closes https://github.com/official-stockfish/Stockfish/pull/4594

bench 2381945
 2023-05-31 09:06:30 +02:00
cj5716
c701745cf2 Remove ss->ttHit condition where ttValue != VALUE_NONE 
Simplification is done at 3 separate places in the code.
Thanks to peregrineshahin for helping me find 2 of such places.
(See original PR #4584)

Passed non-regression test
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 120256 W: 32204 L: 32085 D: 55967
Ptnml(0-2): 292, 12473, 34483, 12584, 296
https://tests.stockfishchess.org/tests/view/646f045968661bfd984325e3

closes https://github.com/official-stockfish/Stockfish/pull/4587

No functional change
 2023-05-25 20:49:11 +02:00