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: Sun Jan 7 21:15:52 2024 +0100
Timestamp: 1704658552

Dual NNUE with L1-128 smallnet

Credit goes to @mstembera for:
- writing the code enabling dual NNUE:
https://github.com/official-stockfish/Stockfish/pull/4898
- the idea of trying L1-128 trained exclusively on high simple eval
positions

The L1-128 smallnet is:
- epoch 399 of a single-stage training from scratch
- trained only on positions from filtered data with high material
difference
- defined by abs(simple_eval) > 1000

```yaml
experiment-name: 128--S1-only-hse-v2

training-dataset:
- /data/hse/S3/dfrc99-16tb7p-eval-filt-v2.min.high-simple-eval-1k.binpack
- /data/hse/S3/leela96-filt-v2.min.high-simple-eval-1k.binpack
- /data/hse/S3/test80-apr2022-16tb7p.min.high-simple-eval-1k.binpack

- /data/hse/S7/test60-2020-2tb7p.v6-3072.high-simple-eval-1k.binpack
- /data/hse/S7/test60-novdec2021-12tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack

- /data/hse/S7/test77-nov2021-2tb7p.v6-3072.min.high-simple-eval-1k.binpack
- /data/hse/S7/test77-dec2021-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test77-jan2022-2tb7p.high-simple-eval-1k.binpack

- /data/hse/S7/test78-jantomay2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test78-juntosep2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack

- /data/hse/S7/test79-apr2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test79-may2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack

# T80 2022
- /data/hse/S7/test80-may2022-16tb7p.high-simple-eval-1k.binpack
- /data/hse/S7/test80-jun2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test80-jul2022-16tb7p.v6-dd.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-aug2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test80-sep2022-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test80-oct2022-16tb7p.v6-dd.high-simple-eval-1k.binpack
- /data/hse/S7/test80-nov2022-16tb7p-v6-dd.min.high-simple-eval-1k.binpack

# T80 2023
- /data/hse/S7/test80-jan2023-3of3-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test80-feb2023-16tb7p-filter-v6-dd.min-mar2023.unmin.high-simple-eval-1k.binpack
- /data/hse/S7/test80-mar2023-2tb7p.v6-sk16.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-apr2023-2tb7p-filter-v6-sk16.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-may2023-2tb7p.v6.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-jun2023-2tb7p.v6-3072.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-jul2023-2tb7p.v6-3072.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-aug2023-2tb7p.v6.min.high-simple-eval-1k.binpack
- /data/hse/S7/test80-sep2023-2tb7p.high-simple-eval-1k.binpack
- /data/hse/S7/test80-oct2023-2tb7p.high-simple-eval-1k.binpack

start-from-engine-test-net: False

nnue-pytorch-branch: linrock/nnue-pytorch/L1-128
engine-test-branch: linrock/Stockfish/L1-128-nolazy
engine-base-branch: linrock/Stockfish/L1-128

num-epochs: 500
lambda: 1.0
```

Experiment yaml configs converted to easy_train.sh commands with:
https://github.com/linrock/nnue-tools/blob/4339954/yaml_easy_train.py

Binpacks interleaved at training time with:
https://github.com/official-stockfish/nnue-pytorch/pull/259

Data filtered for high simple eval positions with:
https://github.com/linrock/nnue-data/blob/32d6a68/filter_high_simple_eval_plain.py
https://github.com/linrock/Stockfish/blob/61dbfe/src/tools/transform.cpp#L626-L655

Training data can be found at:
https://robotmoon.com/nnue-training-data/

Local elo at 25k nodes per move of
L1-128 smallnet (nnue-only eval) vs. L1-128 trained on standard S1 data:
nn-epoch399.nnue : -318.1 +/- 2.1

Passed STC:
https://tests.stockfishchess.org/tests/view/6574cb9d95ea6ba1fcd49e3b
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 62432 W: 15875 L: 15521 D: 31036 Elo +1.97
Ptnml(0-2): 177, 7331, 15872, 7633, 203

Passed LTC:
https://tests.stockfishchess.org/tests/view/6575da2d4d789acf40aaac6e
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 64830 W: 16118 L: 15738 D: 32974 Elo +2.04
Ptnml(0-2): 43, 7129, 17697, 7497, 49

closes https://github.com/official-stockfish/Stockfish/pulls

Bench: 1330050

Co-Authored-By: mstembera <5421953+>
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: mstembera
Date: Sun Jan 7 13:41:50 2024 +0100
Timestamp: 1704631310

Introduce BAD_QUIET movepicker stage

Split quiets into good and bad as we do with captures. When we find
the first quiet move below a certain threshold that has been sorted we
consider all subsequent quiets bad. Inspired by @locutus2 idea to skip
bad captures.

Passed STC:
https://tests.stockfishchess.org/tests/view/6597759f79aa8af82b95fa17
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 138688 W: 35566 L: 35096 D: 68026 Elo +1.18
Ptnml(0-2): 476, 16367, 35183, 16847, 471

Passed LTC:
https://tests.stockfishchess.org/tests/view/6598583c79aa8af82b960ad0
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 84108 W: 21468 L: 21048 D: 41592 Elo +1.73
Ptnml(0-2): 38, 9355, 22858, 9755, 48

closes https://github.com/official-stockfish/Stockfish/pull/4970

Bench: 1336907
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: Sun Jan 7 13:38:55 2024 +0100
Timestamp: 1704631135

Add .git-blame-ignore-revs

Add a `.git-blame-ignore-revs` file which can be used to skip specified
commits when blaming, this is useful to ignore formatting commits, like
clang-format #4790.

Github blame automatically supports this file format, as well as other
third party tools. Git itself needs to be told about the file name to
work, the following command will add it to the current git repo. `git
config blame.ignoreRevsFile .git-blame-ignore-revs`, alternatively one
has to specify it with every blame. `git blame --ignore-revs-file
.git-blame-ignore-revs search.cpp`

Supported since git 2.23.

closes https://github.com/official-stockfish/Stockfish/pull/4969

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: Michael Chaly
Date: Sun Jan 7 13:37:28 2024 +0100
Timestamp: 1704631048

Tweak usage of correction history

Instead of using linear formula use quadratic one. Maximum impact of
correction history is doubled this way, it breaks even with previous
formula on half of maximum value.

Passed STC:
https://tests.stockfishchess.org/tests/view/659591e579aa8af82b95d7e8
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 225216 W: 57616 L: 57019 D: 110581 Elo +0.92
Ptnml(0-2): 747, 26677, 57201, 27198, 785

Passed LTC:
https://tests.stockfishchess.org/tests/view/6596ee0b79aa8af82b95f08a
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 73314 W: 18524 L: 18125 D: 36665 Elo +1.89
Ptnml(0-2): 41, 8159, 19875, 8524, 58

closes https://github.com/official-stockfish/Stockfish/pull/4967

Bench: 1464785
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: Miguel Lahoz
Date: Sun Jan 7 13:37:12 2024 +0100
Timestamp: 1704631032

Remove unneeded operator overload macros

Only Direction type is using two of the enable overload macros.
Aside from this, only two of the overloads are even being used.

Therefore, we can just define the needed overloads and remove the macros.

closes https://github.com/official-stockfish/Stockfish/pull/4966

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: Thu Jan 4 15:56:53 2024 +0100
Timestamp: 1704380213

Remove redundant int cast

Remove a redundant int cast in the calculation of fwdOut. The variable
OutputType is already defined as std::int32_t, which is an integer type, making
the cast unnecessary.

closes https://github.com/official-stockfish/Stockfish/pull/4961

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: Thu Jan 4 15:54:23 2024 +0100
Timestamp: 1704380063

Use type aliases instead of enums for Value types

The primary rationale behind this lies in the fact that enums were not
originally designed to be employed in the manner we currently utilize them.

The Value enum was used like a type alias throughout the code and was often
misused. Furthermore, changing the underlying size of the enum to int16_t broke
everything, mostly because of the operator overloads for the Value enum, were
causing data to be truncated. Since Value is now a type alias, the operator
overloads are no longer required.

Passed Non-Regression STC:
https://tests.stockfishchess.org/tests/view/6593b8bb79aa8af82b95b401
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 235296 W: 59919 L: 59917 D: 115460 Elo +0.00
Ptnml(0-2): 743, 27085, 62054, 26959, 807

closes https://github.com/official-stockfish/Stockfish/pull/4960

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: RainRat
Date: Thu Jan 4 15:51:56 2024 +0100
Timestamp: 1704379916

Fix typo in tbprobe.cpp

closes https://github.com/official-stockfish/Stockfish/pull/4959

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: Thu Jan 4 15:51:04 2024 +0100
Timestamp: 1704379864

Change the Move enum to a class

This changes the Move enum to a class, this way
all move related functions can be moved into the class
and be more self contained.

closes https://github.com/official-stockfish/Stockfish/pull/4958

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: Viren6
Date: Thu Jan 4 15:49:33 2024 +0100
Timestamp: 1704379773

Modify ttPV reduction

This patch modifies ttPV reduction by reducing 1 more unless ttValue is above alpha.

Inspired from @pb00068 https://tests.stockfishchess.org/tests/view/658060796a3b4f6202215f1f

Passed STC:
https://tests.stockfishchess.org/tests/view/6591867679aa8af82b958328
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 37856 W: 9727 L: 9407 D: 18722 Elo +2.94
Ptnml(0-2): 99, 4444, 9568, 4672, 145

Passed LTC:
https://tests.stockfishchess.org/tests/view/6591d9b679aa8af82b958a6c
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 128256 W: 32152 L: 31639 D: 64465 Elo +1.39
Ptnml(0-2): 64, 14364, 34772, 14851, 77

closes https://github.com/official-stockfish/Stockfish/pull/4957

Bench: 1176235
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: Thu Jan 4 15:47:37 2024 +0100
Timestamp: 1704379657

Simplification of partial_insertion_sort formula.

Passed STC:
https://tests.stockfishchess.org/tests/view/6590110879aa8af82b9562e9
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 134880 W: 34468 L: 34355 D: 66057 Elo +0.29
Ptnml(0-2): 476, 16060, 34220, 16243, 441

Passed LTC:
https://tests.stockfishchess.org/tests/view/659156ca79aa8af82b957f07
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 60780 W: 15179 L: 14996 D: 30605 Elo +1.05
Ptnml(0-2): 27, 6847, 16464, 7020, 32

closes https://github.com/official-stockfish/Stockfish/pull/4955

Bench: 1338331
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: Thu Jan 4 15:47:10 2024 +0100
Timestamp: 1704379630

Update copyright year

closes https://github.com/official-stockfish/Stockfish/pull/4954

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: Thu Jan 4 15:45:33 2024 +0100
Timestamp: 1704379533

Silence security alert warning about possible infinite loop

As some have noticed, a security alert has been complaining about a for loop in
our TB code for quite some now. Though it was never a real issue, so not of high
importance.

A few lines earlier the symlen vector is resized
`d->symlen.resize(number<uint16_t, LittleEndian>(data));` while this code seems
odd at first, it resizes the array to at most (2 << 16) - 1 elements, basically
making the infinite loop issue impossible to occur.

closes https://github.com/official-stockfish/Stockfish/pull/4953

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: Joseph Huang
Date: Thu Jan 4 15:45:03 2024 +0100
Timestamp: 1704379503

Lower MultiPV max to MAX_MOVES

Link max value of MultiPV to that of MAX_MOVES which is 256

closes https://github.com/official-stockfish/Stockfish/pull/4951

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: Mon Jan 1 02:31:25 2024 +0100
Timestamp: 1704072685

Fix formatting in search.cpp

fixes the formatting for 1fe562fdf32c153f82929660197f8b97469f76b4
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: Stefan Geschwentner
Date: Sun Dec 31 20:09:09 2023 +0100
Timestamp: 1704049749

Tweak static eval history update

Modify the applied static eval bonus for main and pawn history with different
factors for positive and negative values.

Passed STC:
https://tests.stockfishchess.org/tests/view/659132e179aa8af82b957bb0
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 12512 W: 3308 L: 3027 D: 6177 Elo +7.80
Ptnml(0-2): 32, 1372, 3189, 1609, 54

Passed LTC:
https://tests.stockfishchess.org/tests/view/65913e3d79aa8af82b957cd2
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 35946 W: 9128 L: 8809 D: 18009 Elo +3.08
Ptnml(0-2): 19, 3879, 9862, 4190, 23

closes https://github.com/official-stockfish/Stockfish/pull/4952

Bench: 1392883
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: Michael Chaly
Date: Sun Dec 31 20:00:06 2023 +0100
Timestamp: 1704049206

Introduce static evaluation correction history

Idea from Caissa (https://github.com/Witek902/Caissa) chess engine.

With given pawn structure collect data with how often search result and by how
much it was better / worse than static evalution of position and use it to
adjust static evaluation of positions with given pawn structure. Details:

1. excludes positions with fail highs and moves producing it being a capture;
2. update value is function of not only difference between best value and static
evaluation but also is multiplied by linear function of depth;
3. maximum update value is maximum value of correction history divided by 2;
4. correction history itself is divided by 32 when applied so maximum value of
static evaluation adjustment is 32 internal units.

Passed STC:
https://tests.stockfishchess.org/tests/view/658fc7b679aa8af82b955cac
LLR: 2.96 (-2.94,2.94) <0.00,2.00>
Total: 128672 W: 32757 L: 32299 D: 63616 Elo +1.24
Ptnml(0-2): 441, 15241, 32543, 15641, 470

Passed LTC:
https://tests.stockfishchess.org/tests/view/65903f6979aa8af82b9566f1
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 97422 W: 24626 L: 24178 D: 48618 Elo +1.60
Ptnml(0-2): 41, 10837, 26527, 11245, 61

closes https://github.com/official-stockfish/Stockfish/pull/4950

Bench: 1157852
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 Dec 31 19:58:10 2023 +0100
Timestamp: 1704049090

Mark square_bb() as constexpr

closes https://github.com/official-stockfish/Stockfish/pull/4949

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: Sun Dec 31 19:57:34 2023 +0100
Timestamp: 1704049054

Simplify the improving flag calculation

Passed STC:
https://tests.stockfishchess.org/tests/view/658ec29979aa8af82b9547f6
LLR: 2.93 (-2.94,2.94) <-1.75,0.25>
Total: 93408 W: 23747 L: 23587 D: 46074 Elo +0.60
Ptnml(0-2): 340, 11178, 23527, 11300, 359

Passed LTC:
https://tests.stockfishchess.org/tests/view/658f73e479aa8af82b9555b6
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 64026 W: 15984 L: 15806 D: 32236 Elo +0.97
Ptnml(0-2): 31, 7113, 17552, 7281, 36

closes https://github.com/official-stockfish/Stockfish/pull/4948

Bench: 1143749
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 Dec 31 19:54:27 2023 +0100
Timestamp: 1704048867

Cleanup comments

Tests used to derive some Elo worth comments:
https://tests.stockfishchess.org/tests/view/656a7f4e136acbc573555a31
https://tests.stockfishchess.org/tests/view/6585fb455457644dc984620f

closes https://github.com/official-stockfish/Stockfish/pull/4945

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: Tobias Steinmann
Date: Sun Dec 31 19:51:04 2023 +0100
Timestamp: 1704048664

Update Makefile for android x86-64 builds

For developing an Android GUI it can be helpful to use the Emulator on Windows.
Therefor an android_x86-64 library of Stockfish is needed. It would be nice to
compile it "out-of-the-box".

This change is originally suggested by Craftyawesome

closes https://github.com/official-stockfish/Stockfish/pull/4927

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: Shahin M. Shahin
Date: Sat Dec 30 12:19:48 2023 +0100
Timestamp: 1703935188

Fix scores from reverse futility pruning

This fixes futility pruning return values after recent tweaks, `eval` is
guaranteed to be less than the mate-in range but it can be as low value such
that the average between eval and beta can still fall in the mated-in range when
beta is as low in mated range. i.e. (eval + beta) / 2 being at mated-range which
can break mates.

Passed non-regression STC:
https://tests.stockfishchess.org/tests/view/658f3eed79aa8af82b955139
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 117408 W: 29891 L: 29761 D: 57756 Elo +0.38
Ptnml(0-2): 386, 13355, 31120, 13429, 414

Passed non-regression LTC:
https://tests.stockfishchess.org/tests/view/658f8b7a79aa8af82b9557bd
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 60240 W: 14962 L: 14786 D: 30492 Elo +1.02
Ptnml(0-2): 22, 6257, 17390, 6425, 26

changes signature at higher depth e.g. `128 1 15`

closes https://github.com/official-stockfish/Stockfish/pull/4944

Bench: 1304666
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: Sat Dec 30 11:08:03 2023 +0100
Timestamp: 1703930883

Update default net to nn-b1e55edbea57.nnue

Created by retraining the master big net `nn-0000000000a0.nnue` on the same
dataset with the ranger21 optimizer and more WDL skipping at training time.

More WDL skipping is meant to increase lambda accuracy and train on fewer
misevaluated positions where position scores are unlikely to correlate
with game outcomes. Inspired by:
- repeated reports in discord #events-discuss about SF misplaying due to wrong endgame
evals, possibly due to Leela's endgame weaknesses reflected in training data
- an attempt to reduce the skewed dataset piece count distribution where there
are much more positions with less than 16 pieces, since the target piece count
distribution in the trainer is symmetric around 16

The faster convergence seen with ranger21 is meant to:
- prune experiment ideas more quickly since fewer epochs are needed to reach elo maxima
- research faster potential trainings by shortening each run

```yaml
experiment-name: 2560-S7-Re-514G-ranger21-more-wdl-skip
training-dataset: /data/S6-514G.binpack
early-fen-skipping: 28

start-from-engine-test-net: True
nnue-pytorch-branch: linrock/nnue-pytorch/r21-more-wdl-skip

num-epochs: 1200
lr: 4.375e-4
gamma: 0.995
start-lambda: 1.0
end-lambda: 0.7
```

Experiment yaml configs converted to easy_train.sh commands with:
https://github.com/linrock/nnue-tools/blob/4339954/yaml_easy_train.py

Implementations based off of Sopel's NNUE training & experimentation log:
https://docs.google.com/document/d/1gTlrr02qSNKiXNZ_SuO4-RjK4MXBiFlLE6jvNqqMkAY
- Experiment 336 - ranger21 https://github.com/Sopel97/nnue-pytorch/tree/experiment_336
- Experiment 351 - more WDL skipping

The version of the ranger21 optimizer used is:
https://github.com/lessw2020/Ranger21/blob/b507df6/ranger21/ranger21.py

The dataset is the exact same as in:
https://github.com/official-stockfish/Stockfish/pull/4782

Local elo at 25k nodes per move:
nn-epoch619.nnue : 6.2 +/- 4.2

Passed STC:
https://tests.stockfishchess.org/tests/view/658a029779aa8af82b94fbe6
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 46528 W: 11985 L: 11650 D: 22893 Elo +2.50
Ptnml(0-2): 154, 5489, 11688, 5734, 199

Passed LTC:
https://tests.stockfishchess.org/tests/view/658a448979aa8af82b95010f
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 265326 W: 66378 L: 65574 D: 133374 Elo +1.05
Ptnml(0-2): 153, 30175, 71254, 30877, 204

This was additionally tested with the latest DualNNUE and passed SPRTs:

Passed STC vs. https://github.com/official-stockfish/Stockfish/pull/4919
https://tests.stockfishchess.org/tests/view/658bcd5c79aa8af82b951846
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 296128 W: 76273 L: 75554 D: 144301 Elo +0.84
Ptnml(0-2): 1223, 35768, 73617, 35979, 1477

Passed LTC vs. https://github.com/official-stockfish/Stockfish/pull/4919
https://tests.stockfishchess.org/tests/view/658c988d79aa8af82b95240f
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 75618 W: 19085 L: 18680 D: 37853 Elo +1.86
Ptnml(0-2): 45, 8420, 20497, 8779, 68

closes https://github.com/official-stockfish/Stockfish/pull/4942

Bench: 1304666
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 Dec 30 11:05:19 2023 +0100
Timestamp: 1703930719

Refactor bestvalue adjustment in qsearch

closes https://github.com/official-stockfish/Stockfish/pull/4935

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: Michael Chaly
Date: Sat Dec 30 11:01:32 2023 +0100
Timestamp: 1703930492

Adjust value returned after TT cutoff

Instead of returning value from TT in case of a fail high return mix between it
and beta.

Passed STC:
https://tests.stockfishchess.org/tests/view/658465395457644dc98446c7
LLR: 2.93 (-2.94,2.94) <0.00,2.00>
Total: 220704 W: 56404 L: 55811 D: 108489 Elo +0.93
Ptnml(0-2): 750, 26214, 55921, 26627, 840

Passed LTC:
https://tests.stockfishchess.org/tests/view/6585c3f55457644dc9845db9
LLR: 2.97 (-2.94,2.94) <0.50,2.50>
Total: 124980 W: 31169 L: 30658 D: 63153 Elo +1.42
Ptnml(0-2): 57, 14147, 33603, 14594, 89

closes https://github.com/official-stockfish/Stockfish/pull/4934

Bench: 1191093
see source

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