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: disservin
Date: Sat Jan 28 16:37:29 2023 +0100
Timestamp: 1674920249

Fixed UCI TB win values

This patch results in search values for a TB win/loss to be reported in a way that does not change with normalization, i.e. will be consistent over time.

A value of 200.00 pawns is now reported upon entering a TB won position. Values smaller than 200.00 relate to the distance in plies from the root to the probed position position,
with 1 cp being 1 ply distance.

closes https://github.com/official-stockfish/Stockfish/pull/4353

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: Wed Jan 25 07:51:19 2023 +0100
Timestamp: 1674629479

Rebalance usage of history heuristics in pruning

This patch has multiple effects:

* history heuristics sum in futility pruning now can't exceed some negative value so futility pruning for moves with negative histories should become slightly less aggressive;

* history heuristics are now used in SEE pruning for quiet moves;

Passed STC:
https://tests.stockfishchess.org/tests/view/63cde339c93e8828d0f02e3a
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 88424 W: 23681 L: 23303 D: 41440 Elo +1.49
Ptnml(0-2): 258, 9559, 24219, 9899, 277

Passed LTC:
https://tests.stockfishchess.org/tests/view/63ce9009c93e8828d0f04e4f
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 79536 W: 21223 L: 20843 D: 37470 Elo +1.66
Ptnml(0-2): 22, 7599, 24146, 7979, 22

closes https://github.com/official-stockfish/Stockfish/pull/4355

Bench: 4208265
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: Dubslow
Date: Wed Jan 25 07:48:39 2023 +0100
Timestamp: 1674629319

`stat_bonus`: replace quadratic with nearly identical line

passed stc: https://tests.stockfishchess.org/tests/view/63ca58c90eefe8694a0c4eac
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 287960 W: 76146 L: 76201 D: 135613 Elo -0.07
Ptnml(0-2): 947, 31890, 78307, 31943, 893

passed ltc: https://tests.stockfishchess.org/tests/view/63cc8a51344bb01c191b30f0
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 73784 W: 19559 L: 19402 D: 34823 Elo +0.74
Ptnml(0-2): 33, 7171, 22327, 7328, 33

closes https://github.com/official-stockfish/Stockfish/pull/4352

bench 3990490
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: Mon Jan 23 07:01:32 2023 +0100
Timestamp: 1674453692

Update default net to nn-bc24c101ada0.nnue

Created by retraining the master net with Leela T78 data from Aug+Sep 2022 added to the previous best dataset. Trained with end lambda 0.7 and started with max epoch 800. All positions with ply <= 28 were skipped:

```
python easy_train.py \
--experiment-name leela95-dfrc96-filt-only-T80octnov-T60novdecT78augsepT79aprmay-12tb7p-sk28-lambda7 \
--training-dataset /data/leela95-dfrc96-filt-only-T80octnov-T60novdecT78augsepT79aprmay-12tb7p.binpack \
--nnue-pytorch-branch linrock/nnue-pytorch/misc-fixes-skip-ply-lteq-28 \
--start-from-engine-test-net True \
--gpus "0," \
--start-lambda 1.0 \
--end-lambda 0.7 \
--gamma 0.995 \
--lr 4.375e-4 \
--tui False \
--seed $RANDOM \
--max_epoch 800
```

Around epoch 750, training was manually paused and max epoch increased to 950 before resuming. The additional Leela training data from T78 was prepared in the same way as the previous best dataset.

The exact training data used can be found at:
https://robotmoon.com/nnue-training-data/

While the local elo ratings during this experiment were much lower than in recent master nets, several later epochs had a consistent elo above zero, and this was hypothesized to represent potential strength at slower time controls.

Local elo at 25k nodes per move
leela95-dfrc96-filt-only-T80octnov-T60novdecT78augsepT79aprmay-12tb7p-sk28-lambda7
nn-epoch819.nnue : 0.4 +/- 1.1 (nn-bc24c101ada0.nnue)
nn-epoch799.nnue : 0.3 +/- 1.2
nn-epoch759.nnue : 0.3 +/- 1.1
nn-epoch839.nnue : 0.2 +/- 1.4

Passed STC
https://tests.stockfishchess.org/tests/view/63cabf6f0eefe8694a0c6013
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 41608 W: 11161 L: 10848 D: 19599 Elo +2.61
Ptnml(0-2): 116, 4496, 11281, 4781, 130

Passed LTC
https://tests.stockfishchess.org/tests/view/63cb1856344bb01c191af263
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 76760 W: 20517 L: 20137 D: 36106 Elo +1.72
Ptnml(0-2): 34, 7435, 23070, 7799, 42

closes https://github.com/official-stockfish/Stockfish/pull/4351

bench 3941848
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: Jonathan
Date: Sun Jan 22 13:15:46 2023 +0100
Timestamp: 1674389746

apply if constexpr to additional instances

as a form of documentation, and a hint to the compiler.

closes https://github.com/official-stockfish/Stockfish/pull/4345

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: Stephen Touset
Date: Sun Jan 22 10:55:32 2023 +0100
Timestamp: 1674381332

Remove precomputed SquareBB

Bit-shifting is a single instruction, and should be faster than an array lookup
on supported architectures. Besides (ever so slightly) speeding up the
conversion of a square into a bitboard, we may see minor general performance
improvements due to preserving more of the CPU's existing cache.

passed STC:
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 47280 W: 12469 L: 12271 D: 22540 Elo +1.46
Ptnml(0-2): 128, 4893, 13402, 5087, 130
https://tests.stockfishchess.org/tests/view/63c5cfe618c20f4929c5fe46

Small speedup locally:

```
Result of 20 runs
==================
base (./stockfish.master ) = 1752135 +/- 10943
test (./stockfish.patch ) = 1763939 +/- 10818
diff = +11804 +/- 4731

speedup = +0.0067
P(speedup > 0) = 1.0000

CPU: 16 x AMD Ryzen 9 3950X 16-Core Processor
```

Closes https://github.com/official-stockfish/Stockfish/pull/4343

Bench: 4106793
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: Sun Jan 22 10:54:15 2023 +0100
Timestamp: 1674381255

Update UCI_Elo parameterization

The old parameterization (https://github.com/official-stockfish/Stockfish/pull/2225/files) has now become quite inaccurate.
This updates the formula based on updated results with master. The formula is based on a fit of the Elo results for games
played between master at various skill levels, and various versions of the Stash engine, which have been ranked at CCRL.

```
# PLAYER : RATING ERROR POINTS PLAYED (%)
1 master-skill-19 : 3191.1 40.4 940.0 1707 55
2 master-skill-18 : 3170.3 39.3 1343.0 2519 53
3 master-skill-17 : 3141.3 37.8 2282.0 4422 52
4 master-skill-16 : 3111.2 37.1 2773.0 5423 51
5 master-skill-15 : 3069.5 37.2 2728.5 5386 51
6 master-skill-14 : 3024.8 36.1 2702.0 5339 51
7 master-skill-13 : 2972.9 35.4 2645.5 5263 50
8 master-skill-12 : 2923.1 35.0 2653.5 5165 51
9 master-skill-11 : 2855.5 33.6 2524.0 5081 50
10 master-skill-10 : 2788.3 32.0 2724.5 5511 49
11 stash-bot-v25.0 : 2744.0 31.5 1952.5 3840 51
12 master-skill-9 : 2702.8 30.5 2670.0 5018 53
13 master-skill-8 : 2596.2 28.5 2669.5 4975 54
14 stash-bot-v21.0 : 2561.2 30.0 1338.0 3366 40
15 master-skill-7 : 2499.5 28.5 1934.0 4178 46
16 stash-bot-v20.0 : 2452.6 27.7 1606.5 3378 48
17 stash-bot-v19.0 : 2425.3 26.7 1787.0 3365 53
18 master-skill-6 : 2363.2 26.4 2510.5 4379 57
19 stash-bot-v17.0 : 2280.7 25.4 2209.0 4378 50
20 master-skill-5 : 2203.7 25.3 2859.5 5422 53
21 stash-bot-v15.3 : 2200.0 25.4 1757.0 4383 40
22 stash-bot-v14 : 2145.9 25.5 2890.0 5167 56
23 stash-bot-v13 : 2042.7 25.8 2263.5 4363 52
24 stash-bot-v12 : 1963.4 25.8 1769.5 4210 42
25 master-skill-4 : 1922.9 25.9 2690.0 5399 50
26 stash-bot-v11 : 1873.0 26.3 2203.5 4335 51
27 stash-bot-v10 : 1783.8 27.8 2568.5 4301 60
28 master-skill-3 : 1742.3 27.8 1909.5 4439 43
29 master-skill-2 : 1608.4 29.4 2064.5 4389 47
30 stash-bot-v9 : 1582.6 30.2 2130.0 4230 50
31 master-skill-1 : 1467.6 31.3 2015.5 4244 47
32 stash-bot-v8 : 1452.8 31.5 1953.5 3780 52
33 master-skill-0 : 1320.1 32.9 651.5 2083 31
```

Skill 0 .. 19, now covers CCRL Blitz Elo from 1320 to 3190, approximately.
Indeed, the Elo of stash in this analysis is only to within +- 100 Elo of CCRL,
probably because it depends quite a bit on the opponent pool.

To obtain a skill level for a given Elo number, the above data is fit as a 3rd
degree polynomial Skill(Elo). A quick test confirms the correspondence to the above table:

```
Score of master-elo-2721 vs stash-bot-v21.0: 51 - 16 - 19 [0.703] 86
Elo difference: 150.1 +/- 70.2, LOS: 100.0 %, DrawRatio: 22.1 %
```

closes https://github.com/official-stockfish/Stockfish/pull/4341

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: Sebastian Buchwald
Date: Sun Jan 22 10:51:02 2023 +0100
Timestamp: 1674381062

Fix asm modifiers in add_dpbusd_epi32x2 implementations

The accumulator should be an earlyclobber because it is written before
all input operands are read. Otherwise, the asm code computes a wrong
result if the accumulator shares a register with one of the other input
operands (which happens if we pass in the same expression for the
accumulator and the operand).

Closes https://github.com/official-stockfish/Stockfish/pull/4339

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: Sat Jan 14 08:12:11 2023 +0100
Timestamp: 1673680331

Update default net to nn-1e7ca356472e.nnue

Created by retraining the master net on a dataset composed of:

* The Leela-dfrc_n5000.binpack dataset filtered with depth6 multipv2 search to remove positions with only one good move, in addition to removing positions where either of the two best moves are captures
* The same Leela T80 oct+nov 2022 training data used in recent best datasets
* Additional Leela training data from T60 nov+dec 2021 and T79 apr+may 2022

Trained with end lambda 0.7 and started with max epoch 800. All positions with ply <= 28 were skipped:

```
python easy_train.py \
--experiment-name leela95-dfrc96-mpv-eval-fonly-T80octnov-T79aprmayT60novdec-12tb7p-sk28-lambda7 \
--training-dataset /data/leela95-dfrc96-mpv-eval-fonly-T80octnov-T79aprmayT60novdec-12tb7p.binpack \
--nnue-pytorch-branch linrock/nnue-pytorch/misc-fixes-skip-ply-lteq-28 \
--start-from-engine-test-net True \
--gpus "0," \
--start-lambda 1.0 \
--end-lambda 0.7 \
--gamma 0.995 \
--lr 4.375e-4 \
--tui False \
--seed $RANDOM \
--max_epoch 800
```

Around epoch 780, training was manually paused and max epoch increased to 920 before resuming.

During depth6 multipv2 data filtering, positions were considered to have only one good move if the score of the best move was significantly better than the 2nd best move in a way that changes the outcome of the game:

* the best move leads to a significant advantage while the 2nd best move equalizes or loses
* the best move is about equal while the 2nd best move loses

The modified stockfish branch and exact score thresholds used for filtering are at:
https://github.com/linrock/Stockfish/tree/tools-filter-multipv2-eval-diff/src/filter

About 95% of the Leela portion and 96% of the DFRC portion of the Leela-dfrc_n5000.binpack dataset was filtered. Unfiltered parts of the dataset were left out.

The additional Leela training data from T60 nov+dec 2021 and T79 apr+may 2022 was WDL-rescored with about 12TB of syzygy 7-piece tablebases where the material difference is less than around 6 pawns. Best moves were exported to .plain data files during data conversion with the lc0 rescorer.

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

Local elo at 25k nodes per move
experiment_leela95-dfrc96-mpv-eval-fonly-T80octnov-T79aprmayT60novdec-12tb7p-sk28-lambda7
run_0/nn-epoch899.nnue : 3.8 +/- 1.6

Passed STC
https://tests.stockfishchess.org/tests/view/63bed1f540aa064159b9c89b
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 103344 W: 27392 L: 26991 D: 48961 Elo +1.35
Ptnml(0-2): 333, 11223, 28099, 11744, 273

Passed LTC
https://tests.stockfishchess.org/tests/view/63c010415705810de2deb3ec
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 21712 W: 5891 L: 5619 D: 10202 Elo +4.35
Ptnml(0-2): 12, 2022, 6511, 2304, 7

closes https://github.com/official-stockfish/Stockfish/pull/4338

bench 4106793
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: Mon Jan 9 20:32:58 2023 +0100
Timestamp: 1673292778

Avoid unnecessary string copies

closes https://github.com/official-stockfish/Stockfish/pull/4326

also fixes typo, closes https://github.com/official-stockfish/Stockfish/pull/4332

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: Sebastian Buchwald
Date: Mon Jan 9 20:28:24 2023 +0100
Timestamp: 1673292504

Replace some std::string occurrences with std::string_view

std::string_view is more lightweight than std::string. Furthermore,
std::string_view variables can be declared constexpr.

closes https://github.com/official-stockfish/Stockfish/pull/4328

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: Stefano Di Martino
Date: Mon Jan 9 20:25:13 2023 +0100
Timestamp: 1673292313

Modernize code base a little bit

Removed sprintf() which generated a warning, because of security reasons.
Replace NULL with nullptr
Replace typedef with using
Do not inherit from std::vector. Use composition instead.
optimize mutex-unlocking

closes https://github.com/official-stockfish/Stockfish/pull/4327

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: Sebastian Buchwald
Date: Mon Jan 9 20:18:39 2023 +0100
Timestamp: 1673291919

Warn if a global function has no previous declaration

If a global function has no previous declaration, either the declaration
is missing in the corresponding header file or the function should be
declared static. Static functions are local to the translation unit,
which allows the compiler to apply some optimizations earlier (when
compiling the translation unit rather than during link-time
optimization).

The commit enables the warning for gcc, clang, and mingw. It also fixes
the reported warnings by declaring the functions static or by adding a
header file (benchmark.h).

closes https://github.com/official-stockfish/Stockfish/pull/4325

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: Jake Senne
Date: Mon Jan 9 20:16:17 2023 +0100
Timestamp: 1673291777

Only close file if already open

Ensures that the tablebase file is only closed if already open.

Fixes #4268
Closes https://github.com/official-stockfish/Stockfish/pull/4321

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: candirufish
Date: Mon Jan 9 20:15:08 2023 +0100
Timestamp: 1673291708

On step 18 increase reduction by 2 if not ttmove and cutnode

stc: https://tests.stockfishchess.org/tests/view/63babc9fcd3db0c8d399f723
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 43104 W: 11711 L: 11389 D: 20004 Elo +2.60
Ptnml(0-2): 211, 4518, 11793, 4798, 232

ltc: https://tests.stockfishchess.org/tests/view/63bb1857cd3db0c8d39a0661
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 127104 W: 33810 L: 33339 D: 59955 Elo +1.29
Ptnml(0-2): 39, 12155, 38702, 12608, 48

closes https://github.com/official-stockfish/Stockfish/pull/4334

Bench: 4035725
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: Dubslow
Date: Mon Jan 9 20:12:01 2023 +0100
Timestamp: 1673291521

Late countermove bonus: remove "extraBonus &&"

passed stc: https://tests.stockfishchess.org/tests/view/63a71e409c0589b83751dc25
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 432480 W: 113846 L: 114055 D: 204579 Elo -0.17
Ptnml(0-2): 1164, 48205, 117701, 48016, 1154

passed ltc: https://tests.stockfishchess.org/tests/view/63aba66639af998100ce1aa9
LLR: 2.95 (-2.94,2.94) <-1.75,0.25>
Total: 245344 W: 65309 L: 65317 D: 114718 Elo -0.01
Ptnml(0-2): 117, 24257, 73903, 24307, 88

closes https://github.com/official-stockfish/Stockfish/pull/4322

bench 4379218
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: Wed Jan 4 09:37:02 2023 +0100
Timestamp: 1672821422

Fix stack initialization

This fixes a bug where on line 278 the Stack::staticEvals are
initialized to 0. However VALUE_NONE is defined to be 32002 so
this is a bug in master. It is probably due to the calculation
of improvement, where staticEval prior to rootPos can be accessed.

https://tests.stockfishchess.org/tests/view/63ab91cf39af998100ce1666
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 53736 W: 14285 L: 13955 D: 25496 Elo +2.13
Ptnml(0-2): 121, 5921, 14500, 6159, 167

https://tests.stockfishchess.org/tests/view/63b2af5ee28ed36c814bed52
LLR: 2.94 (-2.94,2.94) <-1.75,0.25>
Total: 33776 W: 9130 L: 8934 D: 15712 Elo +2.02
Ptnml(0-2): 14, 3240, 10185, 3434, 15

closes https://github.com/official-stockfish/Stockfish/pull/4320

Bench: 4068510
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: Mon Jan 2 19:14:05 2023 +0100
Timestamp: 1672683245

Parameter Tweaks

This patch is a parameter tweak that passed both STC and LTC tests.

STC:
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 80944 W: 21557 L: 21189 D: 38198 Elo +1.58
Ptnml(0-2): 192, 8883, 22028, 9103, 266
https://tests.stockfishchess.org/tests/view/63b07fe2d421d8f75795a03b

LTC:
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 30440 W: 8296 L: 8007 D: 14137 Elo +3.30
Ptnml(0-2): 6, 2893, 9143, 3162, 16
https://tests.stockfishchess.org/tests/view/63b167d02ab1290f961644db

closes https://github.com/official-stockfish/Stockfish/pull/4318

Bench: 4182223
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: Mon Jan 2 19:10:14 2023 +0100
Timestamp: 1672683014

Update default net to nn-a3dc078bafc7.nnue

This is a later epoch (epoch 859) from the same experiment run that trained yesterday's master net nn-60fa44e376d9.nnue (epoch 779). The experiment was manually paused around epoch 790 and unpaused with max epoch increased to 900 mainly to get more local elo data without letting the GPU idle.

nn-60fa44e376d9.nnue is from #4314
nn-335a9b2d8a80.nnue is from #4295

Local elo vs. nn-335a9b2d8a80.nnue at 25k nodes per move:
experiment_leela93-dfrc99-filt-only-T80-oct-nov-skip28
run_0/nn-epoch779.nnue (nn-60fa44e376d9.nnue) : 5.0 +/- 1.2
run_0/nn-epoch859.nnue (nn-a3dc078bafc7.nnue) : 5.6 +/- 1.6

Passed STC vs. nn-335a9b2d8a80.nnue
https://tests.stockfishchess.org/tests/view/63ae10495bd1e5f27f13d94f
LLR: 2.95 (-2.94,2.94) <0.00,2.00>
Total: 37536 W: 10088 L: 9781 D: 17667 Elo +2.84
Ptnml(0-2): 110, 4006, 10223, 4325, 104

An LTC test vs. nn-335a9b2d8a80.nnue was paused due to nn-60fa44e376d9.nnue passing LTC first:
https://tests.stockfishchess.org/tests/view/63ae5d34331d5fca5113703b

Passed LTC vs. nn-60fa44e376d9.nnue
https://tests.stockfishchess.org/tests/view/63af1e41465d2b022dbce4e7
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 148704 W: 39672 L: 39155 D: 69877 Elo +1.21
Ptnml(0-2): 59, 14443, 44843, 14936, 71

closes https://github.com/official-stockfish/Stockfish/pull/4319

bench 3984365
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: Mon Jan 2 19:07:38 2023 +0100
Timestamp: 1672682858

Update copyright years

Happy New Year!

closes https://github.com/official-stockfish/Stockfish/pull/4315

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: Sun Jan 1 12:28:51 2023 +0100
Timestamp: 1672572531

Update default net to nn-60fa44e376d9.nnue

Created by retraining the master net on the previous best dataset with additional filtering. No new data was added.

More of the Leela-dfrc_n5000.binpack part of the dataset was pre-filtered with depth6 multipv2 search to remove bestmove captures. About 93% of the previous Leela/SF data and 99% of the SF dfrc data was filtered. Unfiltered parts of the dataset were left out. The new Leela T80 oct+nov data is the same as before. All early game positions with ply count <= 28 were skipped during training by modifying the training data loader in nnue-pytorch.

Trained in a similar way as recent master nets, with a different nnue-pytorch branch for early ply skipping:

python3 easy_train.py \
--experiment-name=leela93-dfrc99-filt-only-T80-oct-nov-skip28 \
--training-dataset=/data/leela93-dfrc99-filt-only-T80-oct-nov.binpack \
--start-from-engine-test-net True \
--nnue-pytorch-branch=linrock/nnue-pytorch/misc-fixes-skip-ply-lteq-28 \
--gpus="0," \
--start-lambda=1.0 \
--end-lambda=0.75 \
--gamma=0.995 \
--lr=4.375e-4 \
--tui=False \
--seed=$RANDOM \
--max_epoch=800 \
--network-testing-threads 20 \
--num-workers 6

For the exact training data used: https://robotmoon.com/nnue-training-data/
Details about the previous best dataset: #4295

Local testing at a fixed 25k nodes:
experiment_leela93-dfrc99-filt-only-T80-oct-nov-skip28
Local Elo: run_0/nn-epoch779.nnue : 5.1 +/- 1.5

Passed STC
https://tests.stockfishchess.org/tests/view/63adb3acae97a464904fd4e8
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 36504 W: 9847 L: 9538 D: 17119 Elo +2.94
Ptnml(0-2): 108, 3981, 9784, 4252, 127

Passed LTC
https://tests.stockfishchess.org/tests/view/63ae0ae25bd1e5f27f13d884
LLR: 2.94 (-2.94,2.94) <0.50,2.50>
Total: 36592 W: 10017 L: 9717 D: 16858 Elo +2.85
Ptnml(0-2): 17, 3461, 11037, 3767, 14

closes https://github.com/official-stockfish/Stockfish/pull/4314

bench 4015511
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 Jan 1 12:26:36 2023 +0100
Timestamp: 1672572396

Remove redundant extern modifier for function declarations

Functions have external linkage by default, so there's no need to
declare them extern.

closes https://github.com/official-stockfish/Stockfish/pull/4308

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: Sebastian Buchwald
Date: Sun Jan 1 12:24:42 2023 +0100
Timestamp: 1672572282

Fix comparison with uninitialized variable

In both modified methods, the variable 'result' is checked to detect
whether the probe operation failed. However, the variable is not
initialized on all paths, so the check might test an uninitialized
value.

A test position (with TB) is given by:

position fen 3K1k2/R7/8/8/8/8/8/R6Q w - - 0 1 moves a1b1 f8g8 b1a1 g8f8 a1b1 f8g8 b1a1

This is now fixed by always initializing the variable.

closes https://github.com/official-stockfish/Stockfish/pull/4309

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: Muzhen Gaming
Date: Sat Dec 24 16:01:50 2022 +0100
Timestamp: 1671894110

Add double bonus for prior countermove fail low

Add a double extra bonus for particularly bad fail low cases. Original idea by Yoshie2000.

STC: https://tests.stockfishchess.org/tests/view/63a2f0d86b5bf07ac7fad543
LLR: 2.94 (-2.94,2.94) <0.00,2.00>
Total: 146488 W: 38992 L: 38532 D: 68964 Elo +1.09
Ptnml(0-2): 385, 16036, 39965, 16450, 408

LTC: https://tests.stockfishchess.org/tests/view/63a3eaeb6b5bf07ac7fafdec
LLR: 2.95 (-2.94,2.94) <0.50,2.50>
Total: 103992 W: 27853 L: 27423 D: 48716 Elo +1.44
Ptnml(0-2): 41, 10029, 31435, 10441, 50

closes https://github.com/official-stockfish/Stockfish/pull/4302

Bench: 3801857
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 24 15:58:51 2022 +0100
Timestamp: 1671893931

Update Elo estimates for terms in search

based on 25k games per term, using the UHO_XXL_+0.90_+1.19.epd book, at STC.

More detailed information in the PR.

closes https://github.com/official-stockfish/Stockfish/pull/4294

No functional change
see source

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