Stockfish Development Versions are build automatically if there are changes on the master branch in the git repository (https://github.com/official-stockfish/Stockfish). Use it at your own risk.
They are compiled with gcc 11.2/mingw 10 on Ubuntu 22.04.

Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Linmiao Xu
Date: Tue Jul 9 18:49:28 2024 +0200
Timestamp: 1720543768

Update default main net to nn-e8bac1c07a5a.nnue

Created by modifying L2 weights from the previous main net (nn-74f1d263ae9a.nnue)
with params found by spsa around 9k / 120k games at 120+1.2.

370 spsa params - L2 weights in nn-74f1d263ae9a.nnue where |val| >= 50
A: 6000, alpha: 0.602, gamma: 0.101
weights: [-127, 127], c_end = 6

To print the spsa params with nnue-pytorch:
```
import features
from serialize import NNUEReader

feature_set = features.get_feature_set_from_name("HalfKAv2_hm")
with open("nn-74f1d263ae9a.nnue", "rb") as f:
model = NNUEReader(f, feature_set).model

c_end = 6
for i in range(8):
for j in range(32):
for k in range(30):
value = int(model.layer_stacks.l2.weight[32 * i + j, k] * 64)
if abs(value) >= 50:
print(f"twoW[{i}][{j}][{k}],{value},-127,127,{c_end},0.0020")
```

Among the 370 params, 229 weights were changed.
avg change: 0.0961 ± 1.67
range: [-4, 3]

The number of weights changed, grouped by layer stack index,
shows more weights were modified in the lower piece count buckets:
[54, 52, 29, 23, 22, 18, 14, 17]

Found with the same method described in:
https://github.com/official-stockfish/Stockfish/pull/5459

Passed STC:
https://tests.stockfishchess.org/tests/view/668aec9a58083e5fd88239e7
LLR: 3.00 (-2.94,2.94) <0.00,2.00>
Total: 52384 W: 13569 L: 13226 D: 25589 Elo +2.27
Ptnml(0-2): 127, 6141, 13335, 6440, 149

Passed LTC:
https://tests.stockfishchess.org/tests/view/668af50658083e5fd8823a0b
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 46974 W: 12006 L: 11668 D: 23300 Elo +2.50
Ptnml(0-2): 25, 4992, 13121, 5318, 31

closes https://github.com/official-stockfish/Stockfish/pull/5466

bench 1300471
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Shawn Xu
Date: Tue Jul 9 18:44:39 2024 +0200
Timestamp: 1720543479

Simplify Probcut Malus

Passed Non-regression STC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 74880 W: 19261 L: 19083 D: 36536 Elo +0.83
Ptnml(0-2): 202, 8861, 19120, 9071, 186
https://tests.stockfishchess.org/tests/view/668a0966eca84f4d25864cba

Passed Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 263916 W: 66690 L: 66718 D: 130508 Elo -0.04
Ptnml(0-2): 125, 29348, 73040, 29320, 125
https://tests.stockfishchess.org/tests/view/668a17e3eca84f4d25864e91

closes https://github.com/official-stockfish/Stockfish/pull/5464

bench 1331408
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stéphane Nicolet
Date: Tue Jul 9 18:42:21 2024 +0200
Timestamp: 1720543341

Fix compilation on Apple

Always use the posix function posix_memalign() as aligned memory
allocator on Apple computers. This should allow to compile Stockfish
out of the box on all versions of Mac OS X.

Patch tested on the following systems (apart from the CI) :
• Mac OS 10.9.6 (arch x86-64-sse41-popcnt) with gcc-10
• Mac OS 10.13.6 (arch x86-64-bmi2) with gcc-10, gcc-14 and clang-11
• Mac OS 14.1.1 (arch apple-silicon) with clang-15

closes https://github.com/official-stockfish/Stockfish/pull/5462

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Tue Jul 9 18:41:36 2024 +0200
Timestamp: 1720543296

Further simplify stat bonuses

Based on recent simplification by linrock Since it completely removed any
special bonuses based on values difference and made it flat stat_bonus(depth +
1) I got an idea that we might as well remove all (depth + 1) bonuses and make
them usual depth bonuses. Also removes weird negative bonus for depth 1 as a
side effect.

Passed STC:
https://tests.stockfishchess.org/tests/view/6689d817eca84f4d25863746
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 18080 W: 4789 L: 4552 D: 8739 Elo +4.55
Ptnml(0-2): 46, 1987, 4727, 2244, 36

Passed LTC:
https://tests.stockfishchess.org/tests/view/6689daa4eca84f4d258639d7
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 109062 W: 27548 L: 27417 D: 54097 Elo +0.42
Ptnml(0-2): 58, 11983, 30293, 12164, 33

Passed direct LTC vs linrock patch:
https://tests.stockfishchess.org/tests/view/668a46f8eca84f4d25866fe9
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 100002 W: 25351 L: 25209 D: 49442 Elo +0.49
Ptnml(0-2): 54, 11119, 27529, 11229, 70

closes https://github.com/official-stockfish/Stockfish/pull/5461

Bench 1175744
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Tue Jul 9 18:36:46 2024 +0200
Timestamp: 1720543006

Fix output for GUI

Fritz 19 can hang with the current way to provide output,
i.e. too much output in a short time for a mate / depth 245 found quickly.

fallout from 25361e514bffb81284d4311601a9f7a4a7ced79b

closes https://github.com/official-stockfish/Stockfish/pull/5460

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Linmiao Xu
Date: Tue Jul 9 18:35:23 2024 +0200
Timestamp: 1720542923

Update default main net to nn-74f1d263ae9a.nnue

Created by setting output weights (256) and biases (8) of the previous main net
nn-ddcfb9224cdb.nnue to values found around 12k / 120k spsa games at 120+1.2

This used modified fishtest dev workers to construct .nnue files from
spsa params, then load them with EvalFile when running tests:
https://github.com/linrock/fishtest/tree/spsa-file-modified-nnue/worker

Inspired by researching loading spsa params from files:
https://github.com/official-stockfish/fishtest/pull/1926

Scripts for modifying nnue files and preparing params:
https://github.com/linrock/nnue-pytorch/tree/no-gpu-modify-nnue

spsa params:
weights: [-127, 127], c_end = 6
biases: [-8192, 8192], c_end = 64

Example of reading output weights and biases from the previous main net using
nnue-pytorch and printing spsa params in a format compatible with fishtest:

```
import features
from serialize import NNUEReader

feature_set = features.get_feature_set_from_name("HalfKAv2_hm")
with open("nn-ddcfb9224cdb.nnue", "rb") as f:
model = NNUEReader(f, feature_set).model

c_end_weights = 6
c_end_biases = 64

for i in range(8):
for j in range(32):
value = round(int(model.layer_stacks.output.weight[i, j] * 600 * 16) / 127)
print(f"oW[{i}][{j}],{value},-127,127,{c_end_weights},0.0020")

for i in range(8):
value = int(model.layer_stacks.output.bias[i] * 600 * 16)
print(f"oB[{i}],{value},-8192,8192,{c_end_biases},0.0020")
```

For more info on spsa tuning params in nets:
https://github.com/official-stockfish/Stockfish/pull/5149
https://github.com/official-stockfish/Stockfish/pull/5254

Passed STC:
https://tests.stockfishchess.org/tests/view/66894d64e59d990b103f8a37
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 32000 W: 8443 L: 8137 D: 15420 Elo +3.32
Ptnml(0-2): 80, 3627, 8309, 3875, 109

Passed LTC:
https://tests.stockfishchess.org/tests/view/6689668ce59d990b103f8b8b
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 172176 W: 43822 L: 43225 D: 85129 Elo +1.20
Ptnml(0-2): 97, 18821, 47633, 19462, 75

closes https://github.com/official-stockfish/Stockfish/pull/5459

bench 1120091
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: MinetaS
Date: Tue Jul 9 18:34:00 2024 +0200
Timestamp: 1720542840

Clean up refutations array in MovePicker

This is a follow-up cleanup to a45c2bc34ae03dd35402e6cf26d515bae1425517.

closes https://github.com/official-stockfish/Stockfish/pull/5458

No functional change
see source
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Linmiao Xu
Date: Tue Jul 9 18:31:02 2024 +0200
Timestamp: 1720542662

Larger bonus when updating quiet stats

Also removes unused arguments to update_all_stats to
fix compiler warnings about unused parameters.

Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/6689a79a0fdd852d63cf52e9
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 26496 W: 6901 L: 6669 D: 12926 Elo +3.04
Ptnml(0-2): 62, 3094, 6715, 3304, 73

Passed non-regression LTC:
https://tests.stockfishchess.org/tests/view/6689a9960fdd852d63cf532d
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 41214 W: 10373 L: 10173 D: 20668 Elo +1.69
Ptnml(0-2): 11, 4491, 11412, 4673, 20

closes https://github.com/official-stockfish/Stockfish/pull/5456

bench 1169958
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Michael Chaly
Date: Tue Jul 9 18:29:09 2024 +0200
Timestamp: 1720542549

Adjust usage of previous statscore in bonus assignments

This patch adjusts usage of previous statscore for bonus assginments - allowing
it for any statscores and clamping it to wider range.

Passed STC:
https://tests.stockfishchess.org/tests/view/66892e76e59d990b103f6a91
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 431520 W: 111767 L: 110872 D: 208881 Elo +0.72
Ptnml(0-2): 1180, 51165, 110133, 52144, 1138

Passed LTC:
https://tests.stockfishchess.org/tests/view/66897176e59d990b103f9605
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 143184 W: 36463 L: 35929 D: 70792 Elo +1.30
Ptnml(0-2): 55, 15540, 39863, 16084, 50

closes https://github.com/official-stockfish/Stockfish/pull/5455

bench 1330556
see source
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Linmiao Xu
Date: Tue Jul 9 18:28:06 2024 +0200
Timestamp: 1720542486

Simplify improving deduction in futility margin

Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/668981d4df142e108ffc9bb4
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 312672 W: 80280 L: 80363 D: 152029 Elo -0.09
Ptnml(0-2): 729, 37198, 80529, 37187, 693

Passed non-regression LTC:
https://tests.stockfishchess.org/tests/view/668988c6df142e108ffca042
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 126042 W: 31971 L: 31857 D: 62214 Elo +0.31
Ptnml(0-2): 50, 13988, 34832, 14100, 51

closes https://github.com/official-stockfish/Stockfish/pull/5454

bench 1100483
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Shawn Xu
Date: Tue Jul 9 18:26:35 2024 +0200
Timestamp: 1720542395

Tweak LMR at Root

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 328192 W: 84751 L: 84014 D: 159427 Elo +0.78
Ptnml(0-2): 758, 38802, 84253, 39511, 772
https://tests.stockfishchess.org/tests/view/6689203959cb3228a4759a49

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 56748 W: 14494 L: 14136 D: 28118 Elo +2.19
Ptnml(0-2): 19, 6089, 15803, 6441, 22
https://tests.stockfishchess.org/tests/view/66892d76e59d990b103f6626

closes https://github.com/official-stockfish/Stockfish/pull/5452

Bench 1253593
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Shawn Xu
Date: Tue Jul 9 18:24:40 2024 +0200
Timestamp: 1720542280

Simplify in-check condition for Probcut-in-check

dont let your memes be dreams !?

Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 512000 W: 132193 L: 132497 D: 247310 Elo -0.21
Ptnml(0-2): 1600, 61170, 130704, 60986, 1540
https://tests.stockfishchess.org/tests/view/66838911c4f539faa03268a2

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 380268 W: 95894 L: 96042 D: 188332 Elo -0.14
Ptnml(0-2): 193, 42861, 104180, 42701, 199
https://tests.stockfishchess.org/tests/view/6688d0550c9d7c1ab33ed5a8

closes https://github.com/official-stockfish/Stockfish/pull/5443

Bench: 1130282
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Shawn Xu
Date: Tue Jul 9 18:20:26 2024 +0200
Timestamp: 1720542026

Simplify Away Move Count Pruning Adjustment

Using Singular Search Result

Passed Non-regression STC:
LLR: 3.01 (-2.94,2.94) <-1.75,0.25>
Total: 62688 W: 16319 L: 16121 D: 30248 Elo +1.10
Ptnml(0-2): 196, 7317, 16104, 7547, 180
https://tests.stockfishchess.org/tests/view/66879bf51b527f04dd477ff9

Passed Non-regression LTC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 116502 W: 29504 L: 29379 D: 57619 Elo +0.37
Ptnml(0-2): 66, 12881, 32226, 13018, 60
https://tests.stockfishchess.org/tests/view/6688629e0c9d7c1ab33ed030

closes https://github.com/official-stockfish/Stockfish/pull/5442

bench 1207930
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Muzhen Gaming
Date: Sat Jul 6 18:00:09 2024 +0200
Timestamp: 1720281609

Simplify ttPv reduction formula

This is a revert of 2046c92.
This patch is based on the fact that the ttPv reduction has proven non-linear scaling (as documented in the code, along with testing guidelines); however, the original patch had (erroneously) not been tested at VLTC or longer.

Simplification STC: https://tests.stockfishchess.org/tests/view/6689266e59cb3228a4759b28
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 100320 W: 25913 L: 25763 D: 48644 Elo +0.52
Ptnml(0-2): 270, 11842, 25750, 12064, 234

Simplification LTC: https://tests.stockfishchess.org/tests/view/66893103e59d990b103f6ab3
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 57078 W: 14466 L: 14282 D: 28330 Elo +1.12
Ptnml(0-2): 34, 6214, 15851, 6414, 26

closes https://github.com/official-stockfish/Stockfish/pull/5448

Bench: 1124658
see source
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Muzhen Gaming
Date: Sat Jul 6 17:58:23 2024 +0200
Timestamp: 1720281503

Simplify internal iterative reductions

This is a revert of cc992e5.
This patch is based on consistent observations that decreasing depth more in IIR generally has a bad scaling behaviour (good at STC, bad at longer time controls).

Simplification STC: https://tests.stockfishchess.org/tests/view/6689266659cb3228a4759b26
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 96992 W: 24977 L: 24824 D: 47191 Elo +0.55
Ptnml(0-2): 251, 11497, 24851, 11642, 255

Simplification LTC: https://tests.stockfishchess.org/tests/view/668930ffe59d990b103f6ab1
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 35808 W: 9185 L: 8980 D: 17643 Elo +1.99
Ptnml(0-2): 25, 3776, 10101, 3973, 29

closes https://github.com/official-stockfish/Stockfish/pull/5447

Bench: 1097766
see source
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Shawn Xu
Date: Sat Jul 6 17:56:31 2024 +0200
Timestamp: 1720281391

Non-functional Fixes & Updates

Fixes a missing default slot for dbg_extremes of, removes a extra newline, and
updates SE elo estimate from
https://tests.stockfishchess.org/tests/view/664ebd1e928b1fb18de4e4b7 while we
are at it.

closes https://github.com/official-stockfish/Stockfish/pull/5446

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: FauziAkram
Date: Sat Jul 6 17:54:22 2024 +0200
Timestamp: 1720281262

Simplify away eval in TM

Passed STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 40160 W: 10523 L: 10309 D: 19328 Elo +1.85
Ptnml(0-2): 129, 4543, 10524, 4753, 131
https://tests.stockfishchess.org/tests/view/6685ab8b99271ae49479dbe9

Passed LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 195672 W: 49681 L: 49639 D: 96352 Elo +0.07
Ptnml(0-2): 112, 20976, 55597, 21060, 91
https://tests.stockfishchess.org/tests/view/6686f27a7092ade1206f7889

closes https://github.com/official-stockfish/Stockfish/pull/5445

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Shawn Xu
Date: Sat Jul 6 17:48:11 2024 +0200
Timestamp: 1720280891

Simplify Away Countermove Heuristic

Passed Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 977824 W: 252072 L: 252888 D: 472864 Elo -0.29
Ptnml(0-2): 2518, 117120, 250560, 116088, 2626
https://tests.stockfishchess.org/tests/view/6683452d95b0d1e881e81541

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 81048 W: 20630 L: 20470 D: 39948 Elo +0.69
Ptnml(0-2): 36, 8915, 22464, 9071, 38
https://tests.stockfishchess.org/tests/view/66886b7b0c9d7c1ab33ed281

closes https://github.com/official-stockfish/Stockfish/pull/5441

bench 1276784
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Muzhen Gaming
Date: Sat Jul 6 17:45:58 2024 +0200
Timestamp: 1720280758

VVLTC search tune

Passed VVLTC 1st sprt: https://tests.stockfishchess.org/tests/view/6688af640c9d7c1ab33ed327
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 16050 W: 4200 L: 3959 D: 7891 Elo +5.22
Ptnml(0-2): 0, 1383, 5018, 1624, 0

Passed VVLTC 2nd sprt: https://tests.stockfishchess.org/tests/view/6688e8900c9d7c1ab33efd60
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 44044 W: 11303 L: 10999 D: 21742 Elo +2.40
Ptnml(0-2): 1, 3973, 13772, 4273, 3

closes https://github.com/official-stockfish/Stockfish/pull/5444

Bench: 992058
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 + SSSE3
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Stéphane Nicolet
Date: Sat Jul 6 17:43:39 2024 +0200
Timestamp: 1720280619

Introduction evaluation grain of 16 (and randomize)

This patch uses an evaluation grain of 16 in order to get more cutoffs in
the alpha-beta algorithm. For a discussion of the efficiency of alpha-beta
related to changes in the number of discrete values of terminal nodes, see
for instance section 9.1.2 of Judea Pearl's classical book "Heuristics" :

https://mat.uab.cat/~alseda/MasterOpt/Judea_Pearl-Heuristics_Intelligent_Search_Strategies_for_Computer_Problem_Solving.pdf

Moreover, we add a small (-1, +1) random component after the quantification
to help the search exploration a little bit. This is similar in spirit to
the (-1, +1) random component already present in the function draw_value()
to make Stockfish more robust in draw evaluations.

passed STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 220960 W: 57249 L: 56668 D: 107043 Elo +0.91
Ptnml(0-2): 499, 26017, 56882, 26568, 514
https://tests.stockfishchess.org/tests/view/668907fb7edfb6f233f999f8

passed LTC :
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 48966 W: 12574 L: 12233 D: 24159 Elo +2.42
Ptnml(0-2): 14, 5233, 13654, 5562, 20
https://tests.stockfishchess.org/tests/view/6689105659cb3228a47598bf

closes https://github.com/official-stockfish/Stockfish/pull/5449

bench: 1336007
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Sat Jul 6 17:42:23 2024 +0200
Timestamp: 1720280543

CI give creditials for the clang-format action

following up from earlier changes

closes https://github.com/official-stockfish/Stockfish/pull/5450

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Fri Jul 5 15:43:49 2024 +0200
Timestamp: 1720187029

Correct and extend PV lines with decisive TB score

Currently (after #5407), SF has the property that any PV line with a decisive
TB score contains the corresponding TB position, with a score that correctly
identifies the depth at which TB are entered. The PV line that follows might
not preserve the game outcome, but can easily be verified and extended based on
TB information. This patch provides this functionality, simply extending the PV
lines on output, this doesn't affect search.

Indeed, if DTZ tables are available, search based PV lines that correspond to
decisive TB scores are verified to preserve game outcome, truncating the line
as needed. Subsequently, such PV lines are extended with a game outcome
preserving line until mate, as a possible continuation. These lines are not
optimal mating lines, but are similar to what a user could produce on a website
like https://syzygy-tables.info/ clicking always the top ranked move, i.e.
minimizing or maximizing DTZ (with a simple tie-breaker for moves that have
identical DTZ), and are thus an just an illustration of how to game can be won.

A similar approach is already in established in
https://github.com/joergoster/Stockfish/tree/matefish2

This also contributes to addressing #5175 where SF can give an incorrect TB
win/loss for positions in TB with a movecounter that doesn't reflect optimal
play. While the full solution requires either TB generated differently, or a
search when ranking rootmoves, current SF will eventually find a draw in these
cases, in practice quite quickly, e.g.
`1kq5/q2r4/5K2/8/8/8/8/7Q w - - 96 1`
`8/8/6k1/3B4/3K4/4N3/8/8 w - - 54 106`

Gives the same results as master on an extended set of test positions from
https://github.com/mcostalba/Stockfish/commit/9173d29c414ddb8f4bec74e4db3ccbe664c66bf9
with the exception of the above mentioned fen where this commit improves.

With https://github.com/vondele/matetrack using 6men TB, all generated PVs verify:
```
Using ../Stockfish/src/stockfish.syzygyExtend on matetrack.epd with --nodes 1000000 --syzygyPath /chess/syzygy/3-4-5-6/WDL:/chess/syzygy/3-4-5-6/DTZ
Engine ID: Stockfish dev-20240704-ff227954
Total FENs: 6555
Found mates: 3299
Best mates: 2582
Found TB wins: 568
```

As repeated DTZ probing could be slow a procedure (100ms+ on HDD, a few ms on
SSD), the extension is only done as long as the time taken is less than half
the `Move Overhead` parameter. For tournaments where these lines might be of
interest to the user, a suitable `Move Overhead` might be needed (e.g. TCEC has
1000ms already).

closes https://github.com/official-stockfish/Stockfish/pull/5414

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Linmiao Xu
Date: Fri Jul 5 15:43:49 2024 +0200
Timestamp: 1720187029

Update 7 stat bonus/malus params

Values found around 119k / 120k spsa games at 60+0.6:
https://tests.stockfishchess.org/tests/view/6683112a192114e61f92f87a

Passed STC:
https://tests.stockfishchess.org/tests/view/66838148c4f539faa0326897
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 40928 W: 10835 L: 10508 D: 19585 Elo +2.78
Ptnml(0-2): 139, 4802, 10254, 5131, 138

Passed LTC:
https://tests.stockfishchess.org/tests/view/668448a87a1863935cee42c6
LLR: 2.96 (-2.94,2.94) <0.50,2.50>
Total: 29208 W: 7559 L: 7253 D: 14396 Elo +3.64
Ptnml(0-2): 17, 3118, 8019, 3442, 8

closes https://github.com/official-stockfish/Stockfish/pull/5439

bench 1138753
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers
Windows x64 + SSSE3
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Joost VandeVondele
Date: Fri Jul 5 15:43:42 2024 +0200
Timestamp: 1720187022

Output from a fix depth onward, instead of 3s.

To avoid output that depends on timing, output currmove and similar only from depth > 30
onward. Current choice of 3s makes the output of the same search depending on
the system load, and doesn't always start at move 1. Depth 30 is nowadays
reached in a few seconds on most systems.

closes https://github.com/official-stockfish/Stockfish/pull/5436

No functional change
see source
Windows x64 for Haswell CPUs
Windows x64 for modern computers + AVX2
Windows x64 for modern computers
Windows x64 + SSSE3
Windows x64
Linux x64 for Haswell CPUs
Linux x64 for modern computers + AVX2
Linux x64 for modern computers
Linux x64 + SSSE3
Linux x64
Author: Disservin
Date: Fri Jul 5 15:35:13 2024 +0200
Timestamp: 1720186513

Use explicit action permissions in CI

Necessary modifications according to changes in the GitHub Action settings.

closes https://github.com/official-stockfish/Stockfish/pull/5437

Follow up from the report by Yaron Avital (yaronav) earlier.

No functional change
see source

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