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: Shawn Xu
Date: Sun Oct 5 09:33:42 2025 +0200
Timestamp: 1759649622

remove clang-format workaround

closes https://github.com/official-stockfish/Stockfish/pull/6332

No functional change
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: Timothy Herchen
Date: Sun Oct 5 09:33:23 2025 +0200
Timestamp: 1759649603

Split accumulator 3-Way

Squeeze a tiny bit more juice from the original idea in #6336 which this is on top of.

https://tests.stockfishchess.org/tests/view/68dddd85fa806e2e8393c0b9
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 156320 W: 40925 L: 40447 D: 74948 Elo +1.06
Ptnml(0-2): 427, 17330, 42172, 17800, 431

4-way doesn't look to be better than this.
https://tests.stockfishchess.org/tests/view/68dde19efa806e2e8393c0c1

closes https://github.com/official-stockfish/Stockfish/pull/6339

No functional change

Co-authored-by: M Stembera <>
see source
Windows x64 for Haswell CPUs
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: Sun Oct 5 09:25:44 2025 +0200
Timestamp: 1759649144

Tweak Correction History Bonus Asymmetrically

Refine the correction history update by applying an asymmetric bonus based on the type of evaluation error. It differentiates between negative corrections and positive corrections.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 165184 W: 43314 L: 42807 D: 79063 Elo +1.07
Ptnml(0-2): 551, 19391, 42261, 19778, 611
https://tests.stockfishchess.org/tests/view/68cae49902c43c969fe7f008

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 243234 W: 62765 L: 62029 D: 118440 Elo +1.05
Ptnml(0-2): 163, 25996, 68551, 26756, 151
https://tests.stockfishchess.org/tests/view/68d1c50dfa806e2e8393aa1f

closes https://github.com/official-stockfish/Stockfish/pull/6338

Bench: 2746404
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: nicolasduhamel
Date: Sun Oct 5 09:23:02 2025 +0200
Timestamp: 1759648982

Adjust aspiration window

Narrow the aspiration window after fail high.

Passed STC:
LLR: 2.98 (-2.94,2.94) <0.00,2.00>
Total: 51296 W: 13550 L: 13207 D: 24539 Elo +2.32
Ptnml(0-2): 165, 5971, 13052, 6276, 184
https://tests.stockfishchess.org/tests/view/68d99afffa806e2e8393b7ae

Passed LTC;
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 87780 W: 22795 L: 22375 D: 42610 Elo +1.66
Ptnml(0-2): 52, 9340, 24694, 9744, 60
https://tests.stockfishchess.org/tests/view/68dae0a6fa806e2e8393baad

See the comments in #6293 discussing the mechanisms leading to issue #6296

closes https://github.com/official-stockfish/Stockfish/pull/6337

Bench: 2336606
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: Sun Oct 5 09:18:16 2025 +0200
Timestamp: 1759648696

Further simplify low ply history in evasions

Passed Non-regression STC (vs #6308):
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 174208 W: 45414 L: 45343 D: 83451 Elo +0.14
Ptnml(0-2): 633, 20324, 45095, 20443, 609
https://tests.stockfishchess.org/tests/view/68c24be359efc3c96b611487

Passed Non-regression LTC (vs #6308):
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 110070 W: 28099 L: 27969 D: 54002 Elo +0.41
Ptnml(0-2): 56, 11919, 30962, 12035, 63
https://tests.stockfishchess.org/tests/view/68c4efa559efc3c96b611dfc

closes https://github.com/official-stockfish/Stockfish/pull/6321

Bench: 2151873
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: Sun Sep 28 21:21:57 2025 +0200
Timestamp: 1759087317

Simplify use of low-ply history in evasions

Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 65024 W: 16991 L: 16804 D: 31229 Elo +1.00
Ptnml(0-2): 182, 7423, 17119, 7602, 186
https://tests.stockfishchess.org/tests/view/68c23f5459efc3c96b6113df

Passed Non-regression LTC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 207312 W: 53126 L: 53095 D: 101091 Elo +0.05
Ptnml(0-2): 126, 21986, 59389, 22041, 114
https://tests.stockfishchess.org/tests/view/68c241e359efc3c96b6113ef

closes https://github.com/official-stockfish/Stockfish/pull/6308

Bench: 2515619
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: Sun Sep 28 21:19:22 2025 +0200
Timestamp: 1759087162

Simplify a separate term in low ply history bonus formula

Passed Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 211200 W: 54887 L: 54860 D: 101453 Elo +0.04
Ptnml(0-2): 719, 24894, 54296, 25023, 668
https://tests.stockfishchess.org/tests/view/68c21e7f59efc3c96b6112c8

Passed Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 217842 W: 55587 L: 55568 D: 106687 Elo +0.03
Ptnml(0-2): 130, 23651, 61313, 23724, 103
https://tests.stockfishchess.org/tests/view/68c230ec59efc3c96b61135a

closes https://github.com/official-stockfish/Stockfish/pull/6307

Bench: 2070860
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: Sun Sep 28 21:14:28 2025 +0200
Timestamp: 1759086868

Simplify away conthist 0

While at it, I also added the scaler note to the Lmrdepth/history formula.

Passed STC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 25376 W: 6660 L: 6423 D: 12293 Elo +3.24
Ptnml(0-2): 77, 2947, 6403, 3184, 77
https://tests.stockfishchess.org/tests/view/68c1ccf759efc3c96b610deb

Passed LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 208464 W: 53371 L: 53342 D: 101751 Elo +0.05
Ptnml(0-2): 110, 22776, 58426, 22815, 105
https://tests.stockfishchess.org/tests/view/68c1d04b59efc3c96b610e13

closes https://github.com/official-stockfish/Stockfish/pull/6304

Bench: 2029296
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: Shawn Xu
Date: Sun Sep 28 21:12:01 2025 +0200
Timestamp: 1759086721

Simplify Probcut Clamp Further

Passed Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 157984 W: 41116 L: 41030 D: 75838 Elo +0.19
Ptnml(0-2): 568, 18570, 40601, 18714, 539
https://tests.stockfishchess.org/tests/view/68b750518f94a4e5a7fe76cd

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 335232 W: 85443 L: 85543 D: 164246 Elo -0.10
Ptnml(0-2): 177, 36616, 94137, 36502, 184
https://tests.stockfishchess.org/tests/view/68bc767259efc3c96b61076b

closes https://github.com/official-stockfish/Stockfish/pull/6303

Bench: 2213844
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: Sun Sep 28 21:08:58 2025 +0200
Timestamp: 1759086538

Remove quiet move streak

Passed Non-regression STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 67712 W: 17744 L: 17555 D: 32413 Elo +0.97
Ptnml(0-2): 204, 8030, 17274, 8069, 279
https://tests.stockfishchess.org/tests/view/68b784628f94a4e5a7fe7706

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 196050 W: 50270 L: 50228 D: 95552 Elo +0.07
Ptnml(0-2): 122, 21465, 54813, 21499, 126
https://tests.stockfishchess.org/tests/view/68ba119d8f94a4e5a7fe7941

closes https://github.com/official-stockfish/Stockfish/pull/6299

Bench: 2238789

Co-authored-by: Daniel Monroe <>
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: Timothy Herchen
Date: Sun Sep 28 21:04:29 2025 +0200
Timestamp: 1759086269

Shave some instructions off a hot loop in affine transform

On x86, GCC generates highly suboptimal code for this loop in its old form,
about 2x as many instructions as necessary. This decreases throughput
especially in an SMT setting. Clang does a better job but this change still has
some improvement. Note that the std::ptrdiff_t type is not optional; using an
unsigned type brings back the bad assembly. (Not sure why, but it seems
reliable on all the GCC versions I tested.)

passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 44672 W: 11841 L: 11527 D: 21304 Elo +2.44
Ptnml(0-2): 165, 4625, 12415, 4993, 138
https://tests.stockfishchess.org/tests/view/68d8111efa806e2e8393b10e

closes https://github.com/official-stockfish/Stockfish/pull/6331

No functional change
see source
Windows x64 for Haswell CPUs
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: Michael Chaly
Date: Sun Sep 28 20:56:36 2025 +0200
Timestamp: 1759085796

Extend nodes pre qsearch only with deep enough tt entries

Modification of current pre qsearch extensions - allowing it only for deep enough tt entries.

Passed STC:
https://tests.stockfishchess.org/tests/view/68c954d302c43c969fe7eea5
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 35872 W: 9548 L: 9236 D: 17088 Elo +3.02
Ptnml(0-2): 101, 4075, 9295, 4341, 124

Passed LTC:
https://tests.stockfishchess.org/tests/view/68ca4e4f02c43c969fe7ef5f
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 107754 W: 27784 L: 27324 D: 52646 Elo +1.48
Ptnml(0-2): 47, 11528, 30300, 11922, 80

closes https://github.com/official-stockfish/Stockfish/pull/6324

bench: 2462792
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: Nonlinear2
Date: Sun Sep 28 20:53:47 2025 +0200
Timestamp: 1759085627

Simplify RFP return value

Passed non-regression STC:
LLR: 2.96 (-2.94,2.94) <-1.75,0.25>
Total: 220800 W: 57351 L: 57332 D: 106117 Elo +0.03
Ptnml(0-2): 726, 26200, 56548, 26181, 745
https://tests.stockfishchess.org/tests/view/68b1db6e6217b8721dca9c67

Passed gainer LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 257820 W: 66286 L: 65523 D: 126011 Elo +1.03
Ptnml(0-2): 118, 27586, 72779, 28269, 158
https://tests.stockfishchess.org/tests/view/68c1d40859efc3c96b610e3d

closes https://github.com/official-stockfish/Stockfish/pull/6310

bench: 2364596
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: FauziAkram
Date: Sun Sep 28 20:51:34 2025 +0200
Timestamp: 1759085494

Double PawnHistory size and update formula

Doubling PAWN_HISTORY_SIZE to 1024. So with that, we can apply a stronger learning signal.
The bonus/malus multipliers in the update_quiet_histories function have been increased accordingly.

Passed STC:
LLR: 2.97 (-2.94,2.94) <0.00,2.00>
Total: 111008 W: 29136 L: 28708 D: 53164 Elo +1.34
Ptnml(0-2): 367, 12870, 28609, 13284, 374
https://tests.stockfishchess.org/tests/view/68c201d659efc3c96b61117e

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 117210 W: 30142 L: 29664 D: 57404 Elo +1.42
Ptnml(0-2): 49, 12532, 32970, 13000, 54
https://tests.stockfishchess.org/tests/view/68c20a6259efc3c96b6111ef

closes https://github.com/official-stockfish/Stockfish/pull/6306

Bench: 2788334
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: Syine Mineta
Date: Sun Sep 28 20:49:24 2025 +0200
Timestamp: 1759085364

Penalty to TT move history on MultiCut

If a reduced search fails high with the TT move excluded, we know that
there are multiple moves that can produce cutoffs. Applying a penalty
to the TT move history reduces extensions for TT moves so that it may
spend a bit more time exploring other moves.

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 263680 W: 68965 L: 68313 D: 126402 Elo +0.86
Ptnml(0-2): 855, 31090, 67336, 31666, 893
https://tests.stockfishchess.org/tests/view/68c1f65a59efc3c96b6110e5

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 61008 W: 15713 L: 15350 D: 29945 Elo +2.07
Ptnml(0-2): 27, 6428, 17235, 6783, 31
https://tests.stockfishchess.org/tests/view/68c1fc5359efc3c96b611141

Passed non-regression VLTC (60+0.6, Threads=8):
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 50340 W: 13003 L: 12830 D: 24507 Elo +1.19
Ptnml(0-2): 3, 4570, 15849, 4747, 1
https://tests.stockfishchess.org/tests/view/68c2056559efc3c96b6111c3

closes https://github.com/official-stockfish/Stockfish/pull/6305

Bench: 2342975
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: Sebastian Buchwald
Date: Sun Sep 28 20:46:42 2025 +0200
Timestamp: 1759085202

Replace deprecated macOS 13 runner image

The macOS 13 runner image will be retired by December 4th, 2025.

closes https://github.com/official-stockfish/Stockfish/pull/6330

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: Robert Nurnberg @ elitebook
Date: Sun Sep 28 20:45:30 2025 +0200
Timestamp: 1759085130

add multithreaded matetrack runs to CI

Add runs with --threads 4 to our matetrack CI. These won't be deterministic, of
course. But they may catch early some multithreading bugs in our mate
reporting.

Motivated by #6293 and #6296.

https://github.com/official-stockfish/Stockfish/pull/6297

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: Disservin
Date: Sun Sep 28 20:43:54 2025 +0200
Timestamp: 1759085034

simplify upload_binaries ci

Previously the upload step used the os of the artifact to create the upload and
used an extra msys2 step. This is in fact not needed and we can do all required
changes on ubuntu instead.

closes https://github.com/official-stockfish/Stockfish/pull/6294

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: Syine Mineta
Date: Sat Sep 13 08:18:52 2025 +0200
Timestamp: 1757744332

Revert "Adjustment of the aspiration window after fail high/low."

This reverts commit bfc7000597b8b5b0899e99bc911f6120a75c6297.

Fixes https://github.com/official-stockfish/Stockfish/issues/6296

After this commit a bug has been reported when the position is close to
mate or being mated. Since no workarounds have been suggested yet, it
is best to revert this commit until a better solution is found.

closes https://github.com/official-stockfish/Stockfish/pull/6309

Bench: 2493363
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: Stefan Geschwentner
Date: Sat Sep 6 07:57:57 2025 +0200
Timestamp: 1757138277

Adjustment of the aspiration window after fail high/low.

For the new bound in the opposite direction of the fail, use a weighted average of alpha, beta and best value +- delta. In the case of a fail high, different average weights are used depending on whether or not there was a best move change during the last search.

The weights are determined from the following two consecutive LTC tunings.

First tuning: https://tests.stockfishchess.org/tests/view/68ab727975da51a345a5ac2e
Second tuning: https://tests.stockfishchess.org/tests/view/68aba3fe75da51a345a5ad52

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 39504 W: 10243 L: 9947 D: 19314 Elo +2.60
Ptnml(0-2): 25, 4182, 11041, 4480, 24
https://tests.stockfishchess.org/tests/view/68acbb6d6217b8721dca95f8

Passed VLTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 91196 W: 23574 L: 23167 D: 44455 Elo +1.55
Ptnml(0-2): 13, 8943, 27276, 9356, 10
https://tests.stockfishchess.org/tests/view/68af64786217b8721dca993d

closes https://github.com/official-stockfish/Stockfish/pull/6292

Bench: 2785713
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: Sat Sep 6 07:55:14 2025 +0200
Timestamp: 1757138114

Reintroduce #6259

Reintroduces af181d9, which no longer regresses on matetrack after #6286

Using ./stockfish on matetrack.epd with --nodes 1000000
Engine ID: Stockfish dev-20250902-adfddd2c
Total FENs: 6554
Found mates: 3490
Best mates: 2429

Passed Non-regression LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 37608 W: 9726 L: 9523 D: 18359 Elo +1.88
Ptnml(0-2): 16, 4001, 10578, 4182, 27
https://tests.stockfishchess.org/tests/view/68b886778f94a4e5a7fe77d9

closes https://github.com/official-stockfish/Stockfish/pull/6289

Bench: 2493363
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: Shawn Xu
Date: Tue Sep 2 20:42:03 2025 +0200
Timestamp: 1756838523

Add scaling note to STC/LTC tunes

It has been repeatedly shown that such tunes are suspectible to become
anti-scaling. Below are some recent examples:

https://github.com/official-stockfish/Stockfish/commit/2e91a8635468e40c89a2303ce50384864d088611
https://github.com/official-stockfish/Stockfish/commit/d11f49b790429c236a1a4169f0d8052635fc03dc

Passed STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 32448 W: 8651 L: 8342 D: 15455 Elo +3.31
Ptnml(0-2): 81, 3695, 8408, 3914, 126
https://tests.stockfishchess.org/tests/view/6899489b0049e8ccef9d64ad

Passed LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 73854 W: 19042 L: 18649 D: 36163 Elo +1.85
Ptnml(0-2): 37, 7908, 20659, 8271, 52
https://tests.stockfishchess.org/tests/view/689abbe7fd8719b088c8d514

Revert VVLTC with STC bound:
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 53802 W: 14030 L: 13740 D: 26032 Elo +1.87
Ptnml(0-2): 5, 4924, 16754, 5212, 6
https://tests.stockfishchess.org/tests/view/68a9a9f575da51a345a5a675

Revert VVLTC with LTC bound:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 53658 W: 14022 L: 13699 D: 25937 Elo +2.09
Ptnml(0-2): 3, 4894, 16712, 5217, 3
https://tests.stockfishchess.org/tests/view/68a8d2b2b6fb3300203bca77

https://tests.stockfishchess.org/tests/view/688cf38bf17748b4d23c8057
https://tests.stockfishchess.org/tests/view/6890bc7792fcad741b804a19

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 74928 W: 19466 L: 19071 D: 36391 Elo +1.83
Ptnml(0-2): 37, 8048, 20901, 8439, 39

Failed Non-regression VLTC:
LLR: -2.94 (-2.94,2.94) <-1.75,0.25>
Total: 57704 W: 14643 L: 14928 D: 28133 Elo -1.72
Ptnml(0-2): 5, 5925, 17280, 5634, 8
https://tests.stockfishchess.org/tests/view/6890bc7792fcad741b804a19

(Note that an STC-tuned version passed non-regression, but was shortly
simplified)

https://github.com/official-stockfish/Stockfish/pull/6040

Passed STC:
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 27776 W: 7352 L: 7054 D: 13370 Elo +3.73
Ptnml(0-2): 68, 3126, 7221, 3386, 87
https://tests.stockfishchess.org/tests/view/680ec0f83629b02d74b1605b

Passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 161304 W: 41432 L: 40864 D: 79008 Elo +1.22
Ptnml(0-2): 61, 17305, 45357, 17863, 66
https://tests.stockfishchess.org/tests/view/680ec7f93629b02d74b16084

Failed Non-regression VVLTC:
LLR: -2.94 (-2.94,2.94) <-1.75,0.25>
Total: 313466 W: 80573 L: 81089 D: 151804 Elo -0.57
Ptnml(0-2): 38, 29689, 97782, 29199, 25
https://tests.stockfishchess.org/tests/view/6810d0533629b02d74b16756

https://github.com/official-stockfish/Stockfish/pull/5907
https://github.com/official-stockfish/Stockfish/pull/5887

Passed LTC with STC bounds:
https://tests.stockfishchess.org/tests/view/67b115dd6c6b9e172ad1592f
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 75756 W: 19393 L: 19044 D: 37319 Elo +1.60
Ptnml(0-2): 60, 8251, 20913, 8588, 66

Passed LTC with LTC bounds:
https://tests.stockfishchess.org/tests/view/67af5f5d6c6b9e172ad15765
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 108126 W: 27880 L: 27412 D: 52834 Elo +1.50
Ptnml(0-2): 85, 11786, 29866, 12228, 98

Revert VVLTC w/ STC bounds:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 56342 W: 14536 L: 14246 D: 27560 Elo +1.79
Ptnml(0-2): 7, 5061, 17741, 5359, 3
https://tests.stockfishchess.org/tests/view/67be4f8ad8d5c2c657c52d10

Revert VVLTC w/ LTC bounds:
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 66562 W: 17364 L: 17016 D: 32182 Elo +1.82
Ptnml(0-2): 3, 6145, 20637, 6493, 3
https://tests.stockfishchess.org/tests/view/67bcd25ff6b602bd7222ea40

closes https://github.com/official-stockfish/Stockfish/pull/6284

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: Shawn Xu
Date: Tue Sep 2 20:41:08 2025 +0200
Timestamp: 1756838468

Simplify SMP Reduction

Passed Non-regression SMP STC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 232784 W: 59845 L: 59841 D: 113098 Elo +0.01
Ptnml(0-2): 289, 26459, 62934, 26379, 331
https://tests.stockfishchess.org/tests/view/68ab96bf75da51a345a5acd6

Passed Non-regression SMP LTC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 374270 W: 95978 L: 96113 D: 182179 Elo -0.13
Ptnml(0-2): 118, 38575, 109888, 38432, 122
https://tests.stockfishchess.org/tests/view/68abcf1c75da51a345a5adb6

closes https://github.com/official-stockfish/Stockfish/pull/6285

Bench: 2667107
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 Sep 2 20:39:02 2025 +0200
Timestamp: 1756838342

simplify stalemate further

Non-regression STC:
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 155200 W: 40650 L: 40562 D: 73988 Elo +0.20
Ptnml(0-2): 533, 17588, 41258, 17700, 521
https://tests.stockfishchess.org/tests/view/68abe11375da51a345a5adec

Non-regression LTC:
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 82824 W: 21442 L: 21287 D: 40095 Elo +0.65
Ptnml(0-2): 51, 8738, 23675, 8901, 47
https://tests.stockfishchess.org/tests/view/68b205606217b8721dca9c8e

10k Stalemate:
Elo: 1.46 ± 1.2 (95%) LOS: 99.0%
Total: 10000 W: 4640 L: 4598 D: 762 Elo +1.46
Ptnml(0-2): 0, 140, 4678, 182, 0
https://tests.stockfishchess.org/tests/view/68b2059b6217b8721dca9c90

closes https://github.com/official-stockfish/Stockfish/pull/6283

Bench: 2431727
see source
Windows x64 for Haswell CPUs
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: Daniel Monroe
Date: Tue Sep 2 20:37:04 2025 +0200
Timestamp: 1756838224

Simplify sign term in quiet histories

Simplify sign term in quiet histories

Passed simplification STC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 497824 W: 129130 L: 129418 D: 239276 Elo -0.20
Ptnml(0-2): 1546, 59040, 128008, 58792, 1526
https://tests.stockfishchess.org/tests/view/68a2a9c1b6fb3300203bc3ed

Passed simplification LTC
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 70830 W: 18185 L: 18016 D: 34629 Elo +0.83
Ptnml(0-2): 36, 7658, 19861, 7821, 39
https://tests.stockfishchess.org/tests/view/68af36c96217b8721dca98d9

closes https://github.com/official-stockfish/Stockfish/pull/6282

Bench: 2393762
see source

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