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 21.10.
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!! latest version !!


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 Aug 6 13:57:30 2022 +0200
Timestamp: 1659787050

Update WDL model for current SF

This updates the WDL model based on the LTC statistics for the two weeks (3M games).

for old results see:

https://github.com/official-stockfish/Stockfish/pull/3981
https://github.com/official-stockfish/Stockfish/pull/3582
https://github.com/official-stockfish/Stockfish/pull/2778

closes https://github.com/official-stockfish/Stockfish/pull/4115

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: Joost VandeVondele
Date: Sat Aug 6 13:53:55 2022 +0200
Timestamp: 1659786835

Update CPU contributors list

Thanks for your contributions!

closes https://github.com/official-stockfish/Stockfish/pull/4116

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: lonfom169
Date: Sat Aug 6 13:52:36 2022 +0200
Timestamp: 1659786756

Reintroduce singularQuietLMR

STC:
LLR: 2.96 (-2.94,2.94) <0.00,2.00>
Total: 88912 W: 23972 L: 23580 D: 41360 Elo +1.53
Ptnml(0-2): 365, 9820, 23712, 10176, 383
https://tests.stockfishchess.org/tests/view/62e9537a400addce2c13399b

LTC:
LLR: 2.97 (-2.94,2.94) <0.50,2.50>
Total: 85672 W: 23607 L: 23192 D: 38873 Elo +1.68
Ptnml(0-2): 219, 8316, 25365, 8703, 233
https://tests.stockfishchess.org/tests/view/62e9a174400addce2c1346e4

closes https://github.com/official-stockfish/Stockfish/pull/4122

Bench: 5921315
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: Sat Aug 6 13:50:01 2022 +0200
Timestamp: 1659786601

Tweak history updates

In general the history update bonus is slightly decreased by 11% which gives a slower saturation speed.
In addition only for main history the divisor is halfed (used history values are doubled to maintain same maximum)
which have an effect in the opposite direction on saturation speed.

STC:
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 157088 W: 42673 L: 42168 D: 72247 Elo +1.12
Ptnml(0-2): 857, 17346, 41642, 17833, 866
https://tests.stockfishchess.org/tests/view/62e5517ab383a712b13867c5

LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 325592 W: 88705 L: 87753 D: 149134 Elo +1.02
Ptnml(0-2): 594, 32288, 96076, 33248, 590
https://tests.stockfishchess.org/tests/view/62e5e4f4b383a712b1387d53

closes https://github.com/official-stockfish/Stockfish/pull/4119

Bench: 5518728
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 Jul 31 11:03:28 2022 +0200
Timestamp: 1659258208

Do more TT cutoffs in case of exact bound

The idea is that these TT entries are considered move valuable in TT replacement scheme - they are always overwriting other entries. So it makes sence for them to produce more aggressive cutoffs.

passed STC
https://tests.stockfishchess.org/tests/view/62e4d407b383a712b1385410
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 96632 W: 26045 L: 25659 D: 44928 Elo +1.39
Ptnml(0-2): 434, 10635, 25770, 11065, 412

passed LTC
https://tests.stockfishchess.org/tests/view/62e523e2b383a712b1386193
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 77960 W: 21363 L: 20989 D: 35608 Elo +1.67
Ptnml(0-2): 190, 7591, 23009, 8035, 155

closes https://github.com/official-stockfish/Stockfish/pull/4114

bench 5820568
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: Sun Jul 31 11:00:31 2022 +0200
Timestamp: 1659258031

remove useClassical depth condition

passed STC:
https://tests.stockfishchess.org/tests/view/62e0c3e98e4fa6ae472695ed
LLR: 2.96 (-2.94,2.94) <-2.25,0.25>
Total: 293568 W: 78934 L: 79151 D: 135483 Elo -0.26
Ptnml(0-2): 1344, 31488, 81366, 31213, 1373

passed LTC:
https://tests.stockfishchess.org/tests/view/62e190aa8e4fa6ae4726b5b5
LLR: 2.98 (-2.94,2.94) <-2.25,0.25>
Total: 187392 W: 50971 L: 51028 D: 85393 Elo -0.11
Ptnml(0-2): 384, 17801, 57369, 17772, 370

other attempts to otherwise tune this parameter failed, bounds 6,7,10,11 failed STC, 8 passed STC but failed LTC

closes https://github.com/official-stockfish/Stockfish/pull/4112

bench 5796377
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: Sun Jul 24 09:18:38 2022 +0200
Timestamp: 1658647118

Simplify reduction condition for cutNodes

LMR: for cutNodes, dont exclude killer moves. This was a prelude to reducing
allNodes, altho that's failed so far.

STC https://tests.stockfishchess.org/tests/view/62d64ad147ae1768b34a27c3
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 37064 W: 10044 L: 9889 D: 17131 Elo +1.45
Ptnml(0-2): 162, 4115, 9828, 4260, 167

LTC https://tests.stockfishchess.org/tests/view/62d66cc047ae1768b34a2b14
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 39832 W: 10796 L: 10659 D: 18377 Elo +1.19
Ptnml(0-2): 69, 3969, 11706, 4100, 72

closes https://github.com/official-stockfish/Stockfish/pull/4109

bench: 5697891
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: Wed Jul 13 18:01:20 2022 +0200
Timestamp: 1657728080

Update default net to nn-ad9b42354671.nnue

using trainer branch https://github.com/glinscott/nnue-pytorch/pull/208 with a slightly
tweaked loss function (power 2.5 instead of 2.6), otherwise same training as in
the previous net update https://github.com/official-stockfish/Stockfish/pull/4100

passed STC:
LLR: 2.97 (-2.94,2.94) <0.00,2.50>
Total: 367536 W: 99465 L: 98573 D: 169498 Elo +0.84
Ptnml(0-2): 1820, 40994, 97117, 42148, 1689
https://tests.stockfishchess.org/tests/view/62cc43fe50dcbecf5fc1c5b8

passed LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 25032 W: 6802 L: 6553 D: 11677 Elo +3.46
Ptnml(0-2): 40, 2424, 7341, 2669, 42
https://tests.stockfishchess.org/tests/view/62ce5f421dacb46e4d5fd277

closes https://github.com/official-stockfish/Stockfish/pull/4107

Bench: 5905619
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 Jul 13 18:00:39 2022 +0200
Timestamp: 1657728039

Simplify away some unneeded code in time management

The lower bound of the clamp is never used since complexity can't be negative and thus is unneeded.

closes https://github.com/official-stockfish/Stockfish/pull/4105

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: Joost VandeVondele
Date: Sat Jul 9 10:58:04 2022 +0200
Timestamp: 1657357084

Limit the researching at same depth.

If the elapsed time is close to the available time, the time management thread can signal that the next iterations should be searched at the same depth (Threads.increaseDepth = false). While the rootDepth increases, the adjustedDepth is kept constant with the searchAgainCounter.

In exceptional cases, when threading is used and the master thread, which controls the time management, signals to not increaseDepth, but by itself takes a long time to finish the iteration, the helper threads can search repeatedly at the same depth. This search finishes more and more quickly, leading to helper threads that report a rootDepth of MAX_DEPTH (245). The latter is not optimal as it is confusing for the user, stops search on these threads, and leads to an incorrect bias in the thread voting scheme. Probably with only a small impact on strength.

This behavior was observed almost two years ago,
see https://github.com/official-stockfish/Stockfish/issues/2717

This patch fixes #2717 by ensuring the effective depth increases at once every four iterations,
even in increaseDepth is false.

Depth 245 searches (for non-trivial positions) were indeed absent with this patch,
but frequent with master in the tests below:
https://discord.com/channels/435943710472011776/813919248455827515/994872720800088095
Total pgns: 2173
Base: 2867
Patch: 0

it passed non-regression testing in various setups:

SMP STC:
https://tests.stockfishchess.org/tests/view/62bfecc96178ffe6394ba036
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 37288 W: 10171 L: 10029 D: 17088 Elo +1.32
Ptnml(0-2): 75, 3777, 10793, 3929, 70

SMP LTC:
https://tests.stockfishchess.org/tests/view/62c08f6f49b62510394be066
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 190568 W: 52125 L: 52186 D: 86257 Elo -0.11
Ptnml(0-2): 70, 17854, 59504, 17779, 77

LTC:
https://tests.stockfishchess.org/tests/view/62c08b6049b62510394bdfb6
LLR: 2.96 (-2.94,2.94) <-2.25,0.25>
Total: 48120 W: 13204 L: 13083 D: 21833 Elo +0.87
Ptnml(0-2): 54, 4458, 14919, 4571, 58

Special thanks to miguel-I, Disservin, ruicoelhopedro and others for analysing the problem,
the data, and coming up with the key insight, needed to fix this longstanding issue.

closes https://github.com/official-stockfish/Stockfish/pull/4104

Bench: 5182295
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: Sat Jul 9 10:53:17 2022 +0200
Timestamp: 1657356797

Time mgmt fix division.

oversight changed the corresponding float division to integer division in a previous tune https://github.com/official-stockfish/Stockfish/commit/442c40b43de8ede1e424efa674c8d45322e3b43c it is stronger to keep the original float division.

green LTC: https://tests.stockfishchess.org/tests/view/62bf34bc0340fb1e0cc934e7
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 38952 W: 10738 L: 10467 D: 17747 Elo +2.42
Ptnml(0-2): 46, 3576, 11968, 3833, 53

yellow STC: https://tests.stockfishchess.org/tests/view/62bff6506178ffe6394ba1d1
LLR: -2.95 (-2.94,2.94) <0.00,2.50>
Total: 226960 W: 61265 L: 61062 D: 104633 Elo +0.31
Ptnml(0-2): 938, 24398, 62582, 24647, 915

further slightly tweaked tests confirm this Elo gain.

closes https://github.com/official-stockfish/Stockfish/pull/4097

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: Tue Jul 5 13:55:50 2022 +0200
Timestamp: 1657022150

Simplify away FRC correction term

Since new net is trained partially using FRC data this part of adjustment that penalises bishops that are locked in the corner is no longer needed - net should "know" this things itself much better.

STC on FRC book :
https://tests.stockfishchess.org/tests/view/62c3031b9e7d9997a12d852f
LLR: 2.96 (-2.94,2.94) <-2.25,0.25>
Total: 22048 W: 3003 L: 2845 D: 16200 Elo +2.49
Ptnml(0-2): 96, 1778, 7149, 1874, 127

LTC on FRC book :
https://tests.stockfishchess.org/tests/view/62c32e939e7d9997a12d8c5e
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 36784 W: 3138 L: 3037 D: 30609 Elo +0.95
Ptnml(0-2): 36, 1842, 14537, 1939, 38

STC on DFRC book :
https://tests.stockfishchess.org/tests/view/62c32efb9e7d9997a12d8c6f
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 20424 W: 3903 L: 3721 D: 12800 Elo +3.10
Ptnml(0-2): 172, 1984, 5724, 2154, 178

LTC on DFRC book :
https://tests.stockfishchess.org/tests/view/62c358c79e7d9997a12d9319
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 53784 W: 7581 L: 7480 D: 38723 Elo +0.65
Ptnml(0-2): 87, 3887, 18856, 3962, 100

closes https://github.com/official-stockfish/Stockfish/pull/4101

bench 5182295
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: Mon Jul 4 15:42:34 2022 +0200
Timestamp: 1656942154

Update default net to nn-3c0054ea9860.nnu

First things first...

this PR is being made from court. Today, Tord and Stéphane, with broad support
of the developer community are defending their complaint, filed in Munich, against ChessBase.
With their products Houdini 6 and Fat Fritz 2, both Stockfish derivatives,
ChessBase violated repeatedly the Stockfish GPLv3 license. Tord and Stéphane have terminated
their license with ChessBase permanently. Today we have the opportunity to present
our evidence to the judge and enforce that termination. To read up, have a look at our blog post
https://stockfishchess.org/blog/2022/public-court-hearing-soon/ and
https://stockfishchess.org/blog/2021/our-lawsuit-against-chessbase/

This PR introduces a net trained with an enhanced data set and a modified loss function in the trainer.
A slight adjustment for the scaling was needed to get a pass on standard chess.

passed STC:
https://tests.stockfishchess.org/tests/view/62c0527a49b62510394bd610
LLR: 2.94 (-2.94,2.94) <0.00,2.50>
Total: 135008 W: 36614 L: 36152 D: 62242 Elo +1.19
Ptnml(0-2): 640, 15184, 35407, 15620, 653

passed LTC:
https://tests.stockfishchess.org/tests/view/62c17e459e7d9997a12d458e
LLR: 2.94 (-2.94,2.94) <0.50,3.00>
Total: 28864 W: 8007 L: 7749 D: 13108 Elo +3.11
Ptnml(0-2): 47, 2810, 8466, 3056, 53

Local testing at a fixed 25k nodes resulted in
Test run1026/easy_train_data/experiments/experiment_2/training/run_0/nn-epoch799.nnue
localElo: 4.2 +- 1.6

The real strength of the net is in FRC and DFRC chess where it gains significantly.

Tested at STC with slightly different scaling:
FRC:
https://tests.stockfishchess.org/tests/view/62c13a4002ba5d0a774d20d4
Elo: 29.78 +-3.4 (95%) LOS: 100.0%
Total: 10000 W: 2007 L: 1152 D: 6841 Elo +29.78
Ptnml(0-2): 31, 686, 2804, 1355, 124
nElo: 59.24 +-6.9 (95%) PairsRatio: 2.06

DFRC:
https://tests.stockfishchess.org/tests/view/62c13a5702ba5d0a774d20d9
Elo: 55.25 +-3.9 (95%) LOS: 100.0%
Total: 10000 W: 2984 L: 1407 D: 5609 Elo +55.25
Ptnml(0-2): 51, 636, 2266, 1779, 268
nElo: 96.95 +-7.2 (95%) PairsRatio: 2.98

Tested at LTC with identical scaling:
FRC:
https://tests.stockfishchess.org/tests/view/62c26a3c9e7d9997a12d6caf
Elo: 16.20 +-2.5 (95%) LOS: 100.0%
Total: 10000 W: 1192 L: 726 D: 8082 Elo +16.20
Ptnml(0-2): 10, 403, 3727, 831, 29
nElo: 44.12 +-6.7 (95%) PairsRatio: 2.08

DFRC:
https://tests.stockfishchess.org/tests/view/62c26a539e7d9997a12d6cb2
Elo: 40.94 +-3.0 (95%) LOS: 100.0%
Total: 10000 W: 2215 L: 1042 D: 6743 Elo +40.94
Ptnml(0-2): 10, 410, 3053, 1451, 76
nElo: 92.77 +-6.9 (95%) PairsRatio: 3.64

This is due to the mixing in a significant fraction of DFRC training data in the final training round. The net is
trained using the easy_train.py script in the following way:

```
python easy_train.py \
--training-dataset=../Leela-dfrc_n5000.binpack \
--experiment-name=2 \
--nnue-pytorch-branch=vondele/nnue-pytorch/lossScan4 \
--additional-training-arg=--param-index=2 \
--start-lambda=1.0 \
--end-lambda=0.75 \
--gamma=0.995 \
--lr=4.375e-4 \
--start-from-engine-test-net True \
--tui=False \
--seed=$RANDOM \
--max_epoch=800 \
--auto-exit-timeout-on-training-finished=900 \
--network-testing-threads 8 \
--num-workers 12
```

where the data set used (Leela-dfrc_n5000.binpack) is a combination of our previous best data set (mix of Leela and some SF data) and DFRC data, interleaved to form:
The data is available in https://drive.google.com/drive/folders/1S9-ZiQa_3ApmjBtl2e8SyHxj4zG4V8gG?usp=sharing
Leela mix: https://drive.google.com/file/d/1JUkMhHSfgIYCjfDNKZUMYZt6L5I7Ra6G/view?usp=sharing
DFRC: https://drive.google.com/file/d/17vDaff9LAsVo_1OfsgWAIYqJtqR8aHlm/view?usp=sharing

The training branch used is
https://github.com/vondele/nnue-pytorch/commits/lossScan4
A PR to the main trainer repo will be made later. This contains a revised loss function, now computing the loss from the score based on the win rate model, which is a more accurate representation than what we had before. Scaling constants are tweaked there as well.

closes https://github.com/official-stockfish/Stockfish/pull/4100

Bench: 5186781
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 Jun 20 08:30:57 2022 +0200
Timestamp: 1655706657

Use NNUE complexity in search, retune related parameters

This builds on ideas of xoto10 and mstembera to use more output from NNUE in the search algorithm.

passed STC:
https://tests.stockfishchess.org/tests/view/62ae454fe7ee5525ef88a957
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 89208 W: 24127 L: 23753 D: 41328 Elo +1.46
Ptnml(0-2): 400, 9886, 23642, 10292, 384

passed LTC:
https://tests.stockfishchess.org/tests/view/62acc6ddd89eb6cf1e0750a1
LLR: 2.93 (-2.94,2.94) <0.50,3.00>
Total: 56352 W: 15430 L: 15115 D: 25807 Elo +1.94
Ptnml(0-2): 44, 5501, 16782, 5794, 55

closes https://github.com/official-stockfish/Stockfish/pull/4088

bench 5332964
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 Jun 20 08:25:50 2022 +0200
Timestamp: 1655706350

LMR: remove `deeper`

...apparently it wasn't doing much anymore. inspired by rufish's recent attempts to improve this.

passed STC:
https://tests.stockfishchess.org/tests/view/62abca2cd89eb6cf1e072c04
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 85576 W: 22766 L: 22683 D: 40127 Elo +0.34
Ptnml(0-2): 362, 9607, 22741, 9742, 336

passed LTC:
https://tests.stockfishchess.org/tests/view/62ac90ffd89eb6cf1e07488f
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 48248 W: 13018 L: 12896 D: 22334 Elo +0.88
Ptnml(0-2): 32, 4773, 14400, 4879, 40

closes https://github.com/official-stockfish/Stockfish/pull/4088

bench 5578988
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: bmc4
Date: Mon Jun 20 08:24:07 2022 +0200
Timestamp: 1655706247

Don't change ttPv at probCut

STC:
LLR: 2.96 (-2.94,2.94) <-2.25,0.25>
Total: 35672 W: 9618 L: 9462 D: 16592 Elo +1.52
Ptnml(0-2): 151, 3890, 9601, 4040, 154
https://tests.stockfishchess.org/tests/view/62ab03f750949cfc241b1965

LTC:
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 54160 W: 14626 L: 14511 D: 25023 Elo +0.74
Ptnml(0-2): 42, 5414, 16056, 5523, 45
https://tests.stockfishchess.org/tests/view/62ab5e6fd89eb6cf1e071b87

closes https://github.com/official-stockfish/Stockfish/pull/4088

bench: 5798229
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: bmc4
Date: Thu Jun 16 07:12:01 2022 +0200
Timestamp: 1655356321

Simplify away condition in ttSave in probCut

Remove condition for tte->save in probCut so it always saves on probCut cutoff.

STC:
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 47848 W: 12921 L: 12782 D: 22145 Elo +1.01
Ptnml(0-2): 207, 5340, 12715, 5431, 231
https://tests.stockfishchess.org/tests/view/62a1f7c87bd8e641e44436f7

LTC:
LLR: 2.97 (-2.94,2.94) <-2.25,0.25>
Total: 132736 W: 35895 L: 35881 D: 60960 Elo +0.04
Ptnml(0-2): 109, 13384, 39360, 13414, 101
https://tests.stockfishchess.org/tests/view/62a2421a7bd8e641e444434f

closes https://github.com/official-stockfish/Stockfish/pull/4069

bench: 5845802
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: Thu Jun 16 07:06:43 2022 +0200
Timestamp: 1655356003

Minor simplifications and cleanup in search

STC: https://tests.stockfishchess.org/tests/view/629d6775593a4a9b6482c1ec
LLR: 2.93 (-2.94,2.94) <-2.25,0.25>
Total: 77416 W: 20683 L: 20589 D: 36144 Elo +0.42
Ptnml(0-2): 317, 8690, 20620, 8744, 337

LTC: https://tests.stockfishchess.org/tests/view/629db4be593a4a9b6482ceef
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 106544 W: 28752 L: 28705 D: 49087 Elo +0.15
Ptnml(0-2): 97, 10692, 31641, 10751, 91

closes https://github.com/official-stockfish/Stockfish/pull/4059

Bench: 5913510
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: ppigazzini
Date: Thu Jun 16 07:03:52 2022 +0200
Timestamp: 1655355832

Restore NDKv21 for GitHub Actions

GitHub updated the versions of NDK installed on the Actions runners
breaking the ARM tests.
Restore the NDKv21 using the GitHub suggested mitigation, see:
https://github.com/actions/virtual-environments/issues/5595

closes https://github.com/official-stockfish/Stockfish/pull/4077

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: Tue Jun 7 08:34:14 2022 +0200
Timestamp: 1654583654

Use qsearch on step 11 if depth is equal to or below 0

larger reduction of depth if no TT entry is found, and go in qsearch as needed.

stc:
https://tests.stockfishchess.org/tests/view/629dfacd593a4a9b6482db72
LLR: 2.93 (-2.94,2.94) <0.00,2.50>
Total: 31920 W: 8591 L: 8322 D: 15007 Elo +2.93
Ptnml(0-2): 127, 3551, 8376, 3738, 168

ltc:
https://tests.stockfishchess.org/tests/view/629e304e593a4a9b6482e451
LLR: 2.95 (-2.94,2.94) <0.50,3.00>
Total: 17488 W: 4842 L: 4614 D: 8032 Elo +4.53
Ptnml(0-2): 13, 1670, 5151, 1896, 14

closes https://github.com/official-stockfish/Stockfish/pull/4056

Bench: 5870283
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: Boštjan Mejak
Date: Tue Jun 7 08:30:07 2022 +0200
Timestamp: 1654583407

Wording of help output and comments.

Improved the output text that is diplayed when executing the 'help' command.
Also, some comments were fixed along the way.

closes https://github.com/official-stockfish/Stockfish/pull/4048
closes https://github.com/official-stockfish/Stockfish/pull/4044

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: Dubslow
Date: Thu Jun 2 07:49:31 2022 +0200
Timestamp: 1654148971

Remove LMR condition for complex pos

Inspired by Kia's similar test: https://tests.stockfishchess.org/tests/view/6292898c1e7cd5f29966fbe0

Passed STC:
https://tests.stockfishchess.org/tests/view/62941588b0d5a7d1b780ed4b
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 266872 W: 70850 L: 71033 D: 124989 Elo -0.24
Ptnml(0-2): 1180, 30114, 70941, 30111, 1090

Passed LTC:
https://tests.stockfishchess.org/tests/view/62964a754628d33daa24f062
LLR: 2.95 (-2.94,2.94) <-2.25,0.25>
Total: 70160 W: 18756 L: 18662 D: 32742 Elo +0.47
Ptnml(0-2): 42, 6976, 20950, 7070, 42

closes https://github.com/official-stockfish/Stockfish/pull/4047

Bench 6237567
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: xoto10
Date: Thu Jun 2 07:47:23 2022 +0200
Timestamp: 1654148843

Blend nnue complexity with classical.

Following mstembera's test of the complexity value derived from nnue values,
this change blends that idea with the old complexity calculation.

STC 10+0.1:
LLR: 2.95 (-2.94,2.94) <0.00,2.50>
Total: 42320 W: 11436 L: 11148 D: 19736 Elo +2.36
Ptnml(0-2): 209, 4585, 11263, 4915, 188
https://tests.stockfishchess.org/tests/live_elo/6295c9239c8c2fcb2bad7fd9

LTC 60+0.6:
LLR: 2.98 (-2.94,2.94) <0.50,3.00>
Total: 34600 W: 9393 L: 9125 D: 16082 Elo +2.69
Ptnml(0-2): 32, 3323, 10319, 3597, 29
https://tests.stockfishchess.org/tests/view/6295fd5d9c8c2fcb2bad88cf

closes https://github.com/official-stockfish/Stockfish/pull/4046

Bench 6078140
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: Thu Jun 2 07:44:22 2022 +0200
Timestamp: 1654148662

cutnode and movecount lmr extension simplification

Passed STC
https://tests.stockfishchess.org/tests/view/6294133cb0d5a7d1b780ece3
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 41072 W: 11052 L: 10908 D: 19112 Elo +1.22
Ptnml(0-2): 153, 4324, 11461, 4422, 176

Passed LTC
ltc: https://tests.stockfishchess.org/tests/view/62947ae6b0d5a7d1b780fe86
LLR: 2.94 (-2.94,2.94) <-2.25,0.25>
Total: 102736 W: 27509 L: 27459 D: 47768 Elo +0.17
Ptnml(0-2): 98, 9734, 31669, 9754, 113

closes https://github.com/official-stockfish/Stockfish/pull/4045

Bench: 6410652
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: Thu Jun 2 07:43:14 2022 +0200
Timestamp: 1654148594

Add info about elo gained from some heuristics

Add info about qsearch and impact of main and continuation histories.

Based on these tests:
https://tests.stockfishchess.org/tests/view/62946ffcb0d5a7d1b780fc7e
https://tests.stockfishchess.org/tests/view/628facb71e7cd5f299669534
https://tests.stockfishchess.org/tests/view/628eade11e7cd5f299666f2e

closes https://github.com/official-stockfish/Stockfish/pull/4041

No functional change.
see source

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