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Author SHA1 Message Date
Stéphane Nicolet
73018a0337 Detect search explosions 
This patch detects some search explosions (due to double extensions in
search.cpp) which can happen in some pathological positions, and takes
measures to ensure progress in search even for these pathological situations.

While a small number of double extensions can be useful during search
(for example to resolve a tactical sequence), a sustained regime of
double extensions leads to search explosion and a non-finishing search.
See the discussion in https://github.com/official-stockfish/Stockfish/pull/3544
and the issue https://github.com/official-stockfish/Stockfish/issues/3532 .

The implemented algorithm is the following:

a) at each node during search, store the current depth in the stack.
   Double extensions are by definition levels of the stack where the
   depth at ply N is strictly higher than depth at ply N-1.

b) during search, calculate for each thread a running average of the
   number of double extensions in the last 4096 visited nodes.

c) if one thread has more than 2% of double extensions for a sustained
   period of time (6 millions consecutive nodes, or about 4 seconds on
   my iMac), we decide that this thread is in an explosion state and
   we calm down this thread by preventing it to do any double extension
   for the next 6 millions nodes.

To calculate the running averages, we also introduced a auxiliary class
generalizing the computations of ttHitAverage variable we already had in
code. The implementation uses an exponential moving average of period 4096
and resolution 1/1024, and all computations are done with integers for
efficiency.

-----------

Example where the patch solves a search explosion:

```
   ./stockfish
   ucinewgame
   position fen 8/Pk6/8/1p6/8/P1K5/8/6B1 w - - 37 130
   go infinite
```

This algorithm does not affect search in normal, non-pathological positions.
We verified, for instance, that the usual bench is unchanged up to depth 20
at least, and that the node numbers are unchanged for a search of the starting
position at depth 32.

-------------

See https://github.com/official-stockfish/Stockfish/pull/3714

Bench: 5575265
 2021-09-23 23:19:06 +02:00
Michael Chaly
e8788d1b32 Combo of various parameter tweaks 
Combination of parameter tweaks in search, evaluation and time management.
Original patches by snicolet xoto10 lonfom169 and Vizvezdenec.

Includes:

* Use bigger grain of positional evaluation more frequently (up to 1 exchange difference in non-pawn-material);
* More extra time according to increment;
* Increase margin for singular extensions;
* Do more aggresive parent node futility pruning.

Passed STC
https://tests.stockfishchess.org/tests/view/6147deab3733d0e0dd9f313d
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 45488 W: 11691 L: 11450 D: 22347
Ptnml(0-2): 145, 5208, 11824, 5395, 172

Passed LTC
https://tests.stockfishchess.org/tests/view/6147f1d53733d0e0dd9f3141
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 62520 W: 15808 L: 15482 D: 31230
Ptnml(0-2): 43, 6439, 17960, 6785, 33

closes https://github.com/official-stockfish/Stockfish/pull/3710

bench 5575265
 2021-09-21 19:48:40 +02:00
xoto10
fd5e77950e Update 2 search parameters after tune. 
A tuning run on 3 search parameters was done with 200k games, narrow ranges (50-150%) and a small value for A (3% of total games) :
https://tests.stockfishchess.org/tests/view/613b5f4b689039fce12e1220

STC 10+0.1 :
LLR: 2.95 (-2.94,2.94) <-0.50,2.50>
Total: 73112 W: 18800 L: 18520 D: 35792
Ptnml(0-2): 205, 8395, 19115, 8597, 244
https://tests.stockfishchess.org/tests/view/613cb8d2689039fce12e1308

LTC 60+0.6 :
LLR: 2.95 (-2.94,2.94) <0.50,3.50>
Total: 45616 W: 11604 L: 11321 D: 22691
Ptnml(0-2): 24, 4769, 12946, 5038, 31
https://tests.stockfishchess.org/tests/view/613d07048253e53e97b55b32

closes https://github.com/official-stockfish/Stockfish/pull/3698

Bench 6504816
 2021-09-12 18:03:56 +02:00
Michael Chaly
30fdbf4328 Decrease depth for cutnodes with no tt move 
By analogy to existing logic of decreasing depth for PvNodes w/o tt move
do the same for cutNodes.

Passed STC
https://tests.stockfishchess.org/tests/view/613abf5a689039fce12e1155
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 90336 W: 23108 L: 22804 D: 44424
Ptnml(0-2): 286, 10316, 23642, 10656, 268

Passed LTC
https://tests.stockfishchess.org/tests/view/613ae330689039fce12e1172
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 37736 W: 9607 L: 9346 D: 18783
Ptnml(0-2): 21, 3917, 10730, 4180, 20

closes https://github.com/official-stockfish/Stockfish/pull/3697

bench 5891181
 2021-09-10 11:50:43 +02:00
Stefan Geschwentner
b7b6b4ba18 Further improve history updates 
Now even double history updates if a search failed low at an expected PV or CUT node.

STC:
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 30736 W: 7891 L: 7674 D: 15171
Ptnml(0-2): 90, 3477, 8017, 3694, 90
https://tests.stockfishchess.org/tests/view/61364ae30cd98ab40c0c9da5

LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 73600 W: 18684 L: 18326 D: 36590
Ptnml(0-2): 41, 7734, 20899, 8078, 48
https://tests.stockfishchess.org/tests/view/6136940f0cd98ab40c0c9df3

closes https://github.com/official-stockfish/Stockfish/pull/3694

Bench: 6030657
 2021-09-07 19:59:14 +02:00
Stefan Geschwentner
c31fc8d163 Improve history updates 
If a search failed low at an expected PV or CUT node do greater history updates.

STC:
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 95112 W: 24293 L: 23982 D: 46837
Ptnml(0-2): 285, 10893, 24906, 11170, 302
https://tests.stockfishchess.org/tests/view/6132aa1a2ffb3c36aceb926f

LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 116352 W: 29450 L: 28975 D: 57927
Ptnml(0-2): 93, 12263, 32984, 12748, 88
https://tests.stockfishchess.org/tests/view/613394d12ffb3c36aceb92f4

closes https://github.com/official-stockfish/Stockfish/pull/3693

Bench: 6130736
 2021-09-06 14:19:47 +02:00
Michael Chaly
e404a7d97c Extend captures and promotions 
This patch introduces extension for captures and promotions. Every capture or
promotion that is not the first move in the list gets extended at PvNodes and
cutNodes. Special thanks to @locutus2 - all my previous attepmts that failed
on this idea were done only for PvNodes - idea to include also cutNodes was
based on his latest passed patch.

STC
https://tests.stockfishchess.org/tests/view/6134abf325b9b35584838574
LLR: 2.95 (-2.94,2.94) <-0.50,2.50>
Total: 188920 W: 47754 L: 47304 D: 93862
Ptnml(0-2): 595, 21754, 49344, 22140, 627

LTC
https://tests.stockfishchess.org/tests/view/613521de25b9b355848385d7
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 8768 W: 2283 L: 2098 D: 4387
Ptnml(0-2): 7, 866, 2452, 1053, 6

closes https://github.com/official-stockfish/Stockfish/pull/3692

bench: 5564555
 2021-09-06 13:59:17 +02:00
VoyagerOne
ad357e147a CMH Pruning Tweak 
Tweak pruning formula by adding up CMH values.

STC:
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 14608 W: 3837 L: 3641 D: 7130
Ptnml(0-2): 27, 1681, 3723, 1815, 58
https://tests.stockfishchess.org/tests/view/612792f362d20cf82b5ad156

LTC:
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 53520 W: 13580 L: 13276 D: 26664
Ptnml(0-2): 28, 5610, 15183, 5908, 31
https://tests.stockfishchess.org/tests/view/6127d27062d20cf82b5ad191

closes https://github.com/official-stockfish/Stockfish/pull/3682

Bench: 5186641
 2021-08-27 21:41:32 +02:00
candirufish
939ffe454d do more LMR extensions for PV nodes 
LMR Pv and depth 6 Extension tweak:

LTC:
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 52488 W: 1542 L: 1394 D: 49552
Ptnml(0-2): 18, 1253, 23552, 1405, 16
https://tests.stockfishchess.org/tests/view/611e49c34977aa1525c9caa7

STC:
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 76216 W: 6000 L: 5784 D: 64432
Ptnml(0-2): 204, 4745, 28006, 4937, 216
https://tests.stockfishchess.org/tests/view/611e0e254977aa1525c9ca89

closes https://github.com/official-stockfish/Stockfish/pull/3666

Bench: 5046381
 2021-08-22 09:05:53 +02:00
bmc4
e57d2d9d47 Simplify Null Move Search Reduction 
slightly simpler formula for reduction computation.

first round of tests:
STC:
LLR: 2.97 (-2.94,2.94) <-2.50,0.50>
Total: 15632 W: 1319 L: 1204 D: 13109
Ptnml(0-2): 33, 956, 5733, 1051, 43
https://tests.stockfishchess.org/tests/view/60bd03c7457376eb8bcaa600

LTC:
LLR: 3.37 (-2.94,2.94) <-2.50,0.50>
Total: 86296 W: 2814 L: 2779 D: 80703
Ptnml(0-2): 33, 2500, 38039, 2551, 25
https://tests.stockfishchess.org/tests/view/60bd1ff0457376eb8bcaa653

recent tests:
STC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 23936 W: 1895 L: 1793 D: 20248
Ptnml(0-2): 40, 1470, 8869, 1526, 63
https://tests.stockfishchess.org/tests/view/611f9b7d4977aa1525c9cb6b

LTC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 62568 W: 1750 L: 1713 D: 59105
Ptnml(0-2): 19, 1560, 28085, 1605, 15
https://tests.stockfishchess.org/tests/view/611fa4814977aa1525c9cb71

functional on high depth

closes https://github.com/official-stockfish/Stockfish/pull/3535

Bench: 5375286
 2021-08-22 09:00:15 +02:00
Joost VandeVondele
dabaf2220f Revert futility pruning patches 
reverts 09b6d28391 and
dbd7f602d3 that significantly impact mate
finding capabilities. For example on ChestUCI_23102018.epd, at 1M nodes,
the number of mates found is nearly reduced 2x without these depth conditions:

       sf6  2091
       sf7  2093
       sf8  2107
       sf9  2062
      sf10  2208
      sf11  2552
      sf12  2563
      sf13  2509
      sf14  2427
    master  1246
   patched  2467

(script for testing at https://github.com/official-stockfish/Stockfish/files/6936412/matecheck.zip)

closes https://github.com/official-stockfish/Stockfish/pull/3641

fixes https://github.com/official-stockfish/Stockfish/issues/3627

Bench: 5467570
 2021-08-05 16:41:07 +02:00
VoyagerOne
a1a83f3869 SEE simplification 
Simplified SEE formula by removing std::min. Should also be easier to tune.

STC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 22656 W: 1836 L: 1729 D: 19091
Ptnml(0-2): 54, 1426, 8267, 1521, 60
https://tests.stockfishchess.org/tests/view/610ae62f2a8a49ac5be79449

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 26248 W: 806 L: 744 D: 24698
Ptnml(0-2): 6, 668, 11715, 728, 7
https://tests.stockfishchess.org/tests/view/610b17ad2a8a49ac5be79466

closes https://github.com/official-stockfish/Stockfish/pull/3643

bench:  4915145
 2021-08-05 16:32:07 +02:00
Stefan Geschwentner
5cd42f6b0b Simplify new cmh pruning thresholds by using directly a quadratic formula. 
This decouples also the stat bonus updates from the threshold which creates less dependencies for tuning of stat bonus parameters.
Perhaps a further fine tuning of the now separated coefficients for constHist[0] and constHist[1] could give further gains.

STC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 78384 W: 6134 L: 6090 D: 66160
Ptnml(0-2): 207, 5013, 28705, 5063, 204
https://tests.stockfishchess.org/tests/view/6106d235afad2da4f4ae3d4b

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 38176 W: 1149 L: 1095 D: 35932
Ptnml(0-2): 6, 1000, 17030, 1038, 14
https://tests.stockfishchess.org/tests/view/6107a080afad2da4f4ae3def

closes https://github.com/official-stockfish/Stockfish/pull/3639

Bench: 5098146
 2021-08-05 08:47:33 +02:00
VoyagerOne
31ebd918ea Futile pruning simplification 
Remove CMH conditions in futile pruning.

STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 93520 W: 7165 L: 7138 D: 79217
Ptnml(0-2): 222, 5923, 34427, 5982, 206
https://tests.stockfishchess.org/tests/view/61083104e50a153c346ef8df

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 59072 W: 1746 L: 1706 D: 55620
Ptnml(0-2): 13, 1562, 26353, 1588, 20
https://tests.stockfishchess.org/tests/view/610894f2e50a153c346ef913

closes https://github.com/official-stockfish/Stockfish/pull/3638

Bench: 5229673
 2021-08-05 08:44:38 +02:00
VoyagerOne
a0fca67da4 CMH Pruning Tweak 
replace CounterMovePruneThreshold by a depth dependent threshold

STC:
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 35512 W: 2718 L: 2552 D: 30242
Ptnml(0-2): 66, 2138, 13194, 2280, 78
https://tests.stockfishchess.org/tests/view/6104442fafad2da4f4ae3b94

LTC:
LLR: 2.96 (-2.94,2.94) <0.50,3.50>
Total: 36536 W: 1150 L: 1019 D: 34367
Ptnml(0-2): 10, 920, 16278, 1049, 11
https://tests.stockfishchess.org/tests/view/6104b033afad2da4f4ae3bbc

closes https://github.com/official-stockfish/Stockfish/pull/3636

Bench: 5848718
 2021-07-31 15:29:19 +02:00
Giacomo Lorenzetti
910d26b5c3 Simplification in LMR 
This commit removes the `!captureOrPromotion` condition from ttCapture reduction and from good/bad history reduction (similar to #3619).

passed STC:
https://tests.stockfishchess.org/tests/view/60fc734ad8a6b65b2f3a7922
LLR: 2.97 (-2.94,2.94) <-2.50,0.50>
Total: 48680 W: 3855 L: 3776 D: 41049
Ptnml(0-2): 118, 3145, 17744, 3206, 127

passed LTC:
https://tests.stockfishchess.org/tests/view/60fce7d5d8a6b65b2f3a794c
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 86528 W: 2471 L: 2450 D: 81607
Ptnml(0-2): 28, 2203, 38777, 2232, 24

closes https://github.com/official-stockfish/Stockfish/pull/3629

Bench: 4951406
 2021-07-26 07:48:58 +02:00
Giacomo Lorenzetti
a85928e7ec Apply good/bad history reduction also when inCheck 
Main idea is that, in some cases, 'in check' situations are not so different from 'not in check' ones.
Trying to use piece count in order to select only a few 'in check' situations have failed LTC testing.
It could be interesting to apply one of those ideas in other parts of the search function.

passed STC:
https://tests.stockfishchess.org/tests/view/60f1b68dd1189bed71812d40
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 53472 W: 4078 L: 4008 D: 45386
Ptnml(0-2): 127, 3297, 19795, 3413, 104

passed LTC:
https://tests.stockfishchess.org/tests/view/60f291e6d1189bed71812de3
LLR: 2.92 (-2.94,2.94) <-2.50,0.50>
Total: 89712 W: 2651 L: 2632 D: 84429
Ptnml(0-2): 60, 2261, 40188, 2294, 53

closes https://github.com/official-stockfish/Stockfish/pull/3619

Bench: 5185789
 2021-07-23 19:02:58 +02:00
Vizvezdenec
d957179df7 Prune illegal moves in qsearch earlier 
The main idea is that illegal moves influencing search or
qsearch obviously can't be any sort of good. The only reason
why initially legality checks for search and qsearch were done
after they actually can influence some heuristics is because
legality check is expensive computationally. Eventually in
search it was moved to the place where it makes sure that
illegal moves can't influence search.

This patch shows that the same can be done for qsearch + it
passed STC with elo-gaining bounds + it removes 3 lines of code
because one no longer needs to increment/decrement movecount
on illegal moves.

passed STC with elo-gaining bounds
https://tests.stockfishchess.org/tests/view/60f20aefd1189bed71812da0
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 61512 W: 4688 L: 4492 D: 52332
Ptnml(0-2): 139, 3730, 22848, 3874, 165

The same version functionally but with moving condition ever earlier
passed LTC with simplification bounds.
https://tests.stockfishchess.org/tests/view/60f292cad1189bed71812de9
LLR: 2.98 (-2.94,2.94) <-2.50,0.50>
Total: 60944 W: 1724 L: 1685 D: 57535
Ptnml(0-2): 11, 1556, 27298, 1597, 10

closes https://github.com/official-stockfish/Stockfish/pull/3618

bench 4709569
 2021-07-23 18:47:30 +02:00
VoyagerOne
36f8d3806b Don't save excluded move eval in TT 
STC:
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 17544 W: 1384 L: 1236 D: 14924
Ptnml(0-2): 37, 1031, 6499, 1157, 48
https://tests.stockfishchess.org/tests/view/60ec8d9bd1189bed71812999

LTC:
LLR: 2.95 (-2.94,2.94) <0.50,3.50>
Total: 26136 W: 823 L: 707 D: 24606
Ptnml(0-2): 6, 643, 11656, 755, 8
https://tests.stockfishchess.org/tests/view/60ecb11ed1189bed718129ba

closes https://github.com/official-stockfish/Stockfish/pull/3614

Bench: 5505251
 2021-07-13 17:35:20 +02:00
Vizvezdenec
dbd7f602d3 Remove second futility pruning depth limit 
This patch removes futility pruning lmrDepth limit for futility pruning at parent nodes.
Since it's already capped by margin that is a function of lmrDepth there is no need to extra cap it with lmrDepth.

passed STC
https://tests.stockfishchess.org/tests/view/60e9b5dfd1189bed71812777
LLR: 2.97 (-2.94,2.94) <-2.50,0.50>
Total: 14872 W: 1264 L: 1145 D: 12463
Ptnml(0-2): 37, 942, 5369, 1041, 47

passed LTC
https://tests.stockfishchess.org/tests/view/60e9c635d1189bed71812790
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 40336 W: 1280 L: 1225 D: 37831
Ptnml(0-2): 24, 1057, 17960, 1094, 33

closes https://github.com/official-stockfish/Stockfish/pull/3612

bench: 5064969
 2021-07-13 17:33:20 +02:00
Vizvezdenec
09b6d28391 Remove futility pruning depth limit 
This patch removes futility pruning depth limit for child node futility pruning.
In current master it was double capped by depth and by futility margin, which is also a function of depth, which didn't make much sense.

passed STC
https://tests.stockfishchess.org/tests/view/60e2418f9ea99d7c2d693e64
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 116168 W: 9100 L: 9097 D: 97971
Ptnml(0-2): 319, 7496, 42476, 7449, 344

passed LTC
https://tests.stockfishchess.org/tests/view/60e3374f9ea99d7c2d693f20
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 43304 W: 1282 L: 1231 D: 40791
Ptnml(0-2): 8, 1126, 19335, 1173, 10

closes https://github.com/official-stockfish/Stockfish/pull/3606

bench 4965493
 2021-07-13 17:23:30 +02:00
candirufish
ec8dfe7315 no cut node reduction for killer moves. 
stc:
LLR: 2.95 (-2.94,2.94) <-0.50,2.50>
Total: 44344 W: 3474 L: 3294 D: 37576
Ptnml(0-2): 117, 2710, 16338, 2890, 117
https://tests.stockfishchess.org/tests/view/60d8ea673beab81350ac9eb8

ltc:
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 82600 W: 2638 L: 2441 D: 77521
Ptnml(0-2): 38, 2147, 36749, 2312, 54
https://tests.stockfishchess.org/tests/view/60d9048f3beab81350ac9eed

closes https://github.com/official-stockfish/Stockfish/pull/3600

Bench: 5160239
 2021-07-03 09:44:05 +02:00
bmc4
e47b74457e Simplify Reductions Initialization 
passed

STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 45032 W: 3600 L: 3518 D: 37914
Ptnml(0-2): 111, 2893, 16435, 2957, 120
https://tests.stockfishchess.org/tests/view/60d2655d40925195e7a6c527

LTC:
LLR: 3.00 (-2.94,2.94) <-2.50,0.50>
Total: 25728 W: 786 L: 722 D: 24220
Ptnml(0-2): 5, 650, 11494, 706, 9
https://tests.stockfishchess.org/tests/view/60d2b14240925195e7a6c577

closes https://github.com/official-stockfish/Stockfish/pull/3584

bench: 4602977
 2021-06-28 21:12:04 +02:00
Stéphane Nicolet
ed436a36ba Remove the Contempt UCI option 
This patch removes the UCI option for setting Contempt in classical evaluation.

It is exactly equivalent to using Contempt=0 for the UCI contempt value and keeping
the dynamic part in the algo (renaming this dynamic part `trend` to better describe
what it does). We have tried quite hard to implement a working Contempt feature for
NNUE but nothing really worked, so it is probably time to give up.

Interested chess fans wishing to keep playing with the UCI option for Contempt and
use it with the classical eval are urged to download the version tagged "SF_Classical"
of Stockfish (dated 31 July 2020), as it was the last version where our search
algorithm was tuned for the classical eval and is probably our strongest classical
player ever: https://github.com/official-stockfish/Stockfish/tags

Passed STC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 72904 W: 6228 L: 6175 D: 60501
Ptnml(0-2): 221, 5006, 25971, 5007, 247
https://tests.stockfishchess.org/tests/view/60c98bf9457376eb8bcab18d

Passed LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 45168 W: 1601 L: 1547 D: 42020
Ptnml(0-2): 38, 1331, 19786, 1397, 32
https://tests.stockfishchess.org/tests/view/60c9c7fa457376eb8bcab1bb

closes https://github.com/official-stockfish/Stockfish/pull/3575

Bench: 4947716
 2021-06-21 22:58:56 +02:00
bmc4
55e69dc88d Simplify reduction when best move doesn't change frequently. 
STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 40400 W: 3468 L: 3377 D: 33555
Ptnml(0-2): 134, 2734, 14388, 2795, 149
https://tests.stockfishchess.org/tests/view/60c93e5a457376eb8bcab15f

LTC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 34200 W: 1190 L: 1128 D: 31882
Ptnml(0-2): 22, 998, 15001, 1054, 25
https://tests.stockfishchess.org/tests/view/60c96a1a457376eb8bcab180

closes https://github.com/official-stockfish/Stockfish/pull/3559

bench: 5629669
 2021-06-17 02:08:33 +02:00
Vizvezdenec
e1f181ee64 Do less LMR extensions 
This patch restricts LMR extensions (of non-transposition table moves) from being
used when the transposition table move was extended by two plies via singular
extension. This may serve to limit search explosions in certain positions.

This makes a lot of sense because the precondition for the tt-move to have been
singular extended by two plies is that the result of the alternate search (with
excluded the tt-move) has been a hard fail low: it is natural to later search less
for non tt-moves in this situation.

The current state of depth/extensions/reductions management is getting quite tricky
in our search algo, see https://github.com/official-stockfish/Stockfish/pull/3546#issuecomment-860174549
for some discussion. Suggestions welcome!

Passed STC
https://tests.stockfishchess.org/tests/view/60c3f293457376eb8bcaac8d
LLR: 2.95 (-2.94,2.94) <-0.50,2.50>
Total: 117984 W: 9698 L: 9430 D: 98856
Ptnml(0-2): 315, 7708, 42703, 7926, 340

passed LTC
https://tests.stockfishchess.org/tests/view/60c46ea5457376eb8bcaacc7
LLR: 2.97 (-2.94,2.94) <0.50,3.50>
Total: 11280 W: 401 L: 302 D: 10577
Ptnml(0-2): 2, 271, 4998, 364, 5

closes https://github.com/official-stockfish/Stockfish/pull/3546

Bench: 4709974
 2021-06-13 12:00:20 +02:00
Joost VandeVondele
559942d64d Limit double extensions 
Double extensions can lead to search explosions, for specific positions.
Currently, however, these double extensions are worth about 10Elo and cannot
be removed. This patch instead limits the number of double extensions given
to a maximum of 3.

This fixes https://github.com/official-stockfish/Stockfish/issues/3532
where the following testcase was shown to be problematic:

```
uci
setoption name Hash value 4
setoption name Contempt value 0
ucinewgame
position fen 8/Pk6/8/1p6/8/P1K5/8/6B1 w - - 37 130
go depth 20
```

passed STC:
https://tests.stockfishchess.org/tests/view/60c13161457376eb8bcaaa0f
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 73256 W: 6114 L: 6062 D: 61080
Ptnml(0-2): 222, 4912, 26306, 4968, 220

passed LTC:
https://tests.stockfishchess.org/tests/view/60c196fb457376eb8bcaaa6b
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 166440 W: 5559 L: 5594 D: 155287
Ptnml(0-2): 106, 4921, 73197, 4894, 102

closes https://github.com/official-stockfish/Stockfish/pull/3544

Bench: 5067605
 2021-06-11 20:33:24 +02:00
bmc4
785b708097 Simplify promotion move generator 
This patch removes Knight promotion checks from Captures. As a consequence,
it also removes this underpromotion from qsearch.

STC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 37776 W: 3113 L: 3023 D: 31640
Ptnml(0-2): 103, 2419, 13755, 2507, 104
https://tests.stockfishchess.org/tests/view/60be6a06457376eb8bcaa775

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 39760 W: 1257 L: 1203 D: 37300
Ptnml(0-2): 11, 1079, 17646, 1133, 11
https://tests.stockfishchess.org/tests/view/60beb972457376eb8bcaa7c5

closes https://github.com/official-stockfish/Stockfish/pull/3536

Bench: 5530620
 2021-06-08 20:16:20 +02:00
bmc4
999e142c54 Reduce in LMR reduction on PvNode 
reduce reduction in LMR by 1 on PvNode.

STC:
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 266080 W: 22438 L: 21996 D: 221646
Ptnml(0-2): 774, 17874, 95376, 18168, 848
https://tests.stockfishchess.org/tests/view/60bc0661457376eb8bcaa4bb

LTC:
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 20144 W: 698 L: 587 D: 18859
Ptnml(0-2): 2, 529, 8906, 626, 9
https://tests.stockfishchess.org/tests/view/60bcc3f2457376eb8bcaa58d

closes https://github.com/official-stockfish/Stockfish/pull/3534

bench: 5173012
 2021-06-06 21:22:39 +02:00
bmc4
0b7cc8bd2f Introducing NodeType Root 
We transform rootNode into constexpr by adding a new NodeType `Root`,
which causes a speed up.

Local test:
```
Build Tester: 1.4.7.0
Windows 10 (Version 10.0, Build 0, 64-bit Edition)
Intel(R) Core(TM) i7-8750H CPU @ 2.20GHz
SafeMode: No
Running In VM: No
HyperThreading Enabled: Yes
CPU Warmup: Yes
Command Line: bench
Tests per Build: 25
ANOVA: n/a

                Engine# (NPS)                     Speedup     Sp     Conf. 95%    S.S.
patch  (920.179,4) ---> master  (906.329,2)  --->  1,528%  20.336,5     Yes        No
```

---------

STC:
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 98216 W: 8348 L: 8102 D: 81766
Ptnml(0-2): 295, 6357, 35549, 6621, 286
https://tests.stockfishchess.org/tests/view/60b797e2457376eb8bcaa0ab

Yellow LTC:
LLR: -2.95 (-2.94,2.94) <0.50,3.50>
Total: 76936 W: 2651 L: 2626 D: 71659
Ptnml(0-2): 29, 2233, 33916, 2264, 26
https://tests.stockfishchess.org/tests/view/60b80d6d457376eb8bcaa145

closes https://github.com/official-stockfish/Stockfish/pull/3522

No functional change
 2021-06-04 01:23:49 +02:00
xoto10
9353e72103 Make extra time for bestMoveInstability dependent on rootdepth. 
This change allocates more base time to moves and makes the additional time added for best move instability dependent on rootdepth.

STC 10+0.1 :
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 19432 W: 1711 L: 1553 D: 16168
Ptnml(0-2): 47, 1250, 6989, 1358, 72
https://tests.stockfishchess.org/tests/view/60b8cd41457376eb8bcaa1ad

LTC 60+0.6 :
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 22480 W: 810 L: 693 D: 20977
Ptnml(0-2): 9, 603, 9902, 714, 12
https://tests.stockfishchess.org/tests/view/60b8e5bf457376eb8bcaa1e6

closes https://github.com/official-stockfish/Stockfish/pull/3526

Bench 4364128
 2021-06-03 21:22:56 +02:00
Stefan Geschwentner
95f73ff393 Remove formerPV variable. 
STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 75672 W: 6546 L: 6496 D: 62630
Ptnml(0-2): 238, 5274, 26761, 5326, 237
https://tests.stockfishchess.org/tests/view/60b349c0ec0c03148cbed055

LTC:
LLR: 2.98 (-2.94,2.94) <-2.50,0.50>
Total: 137816 W: 4676 L: 4689 D: 128451
Ptnml(0-2): 52, 4237, 60354, 4202, 63
https://tests.stockfishchess.org/tests/view/60b38970ec0c03148cbed075

closes https://github.com/official-stockfish/Stockfish/pull/3515

Bench: 4892288
 2021-06-01 23:21:00 +02:00
J. Oster
9fd5b44d60 Pre-initialize ss->ply 
We pre-initialize ss->ply over the whole stack. There is no need
to re-assign the same value(s) over and over again while searching.
Probably a tiny speedup on longer searches.

Tested for no regression:

STC
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 25784 W: 2205 L: 2101 D: 21478
Ptnml(0-2): 62, 1660, 9368, 1716, 86
https://tests.stockfishchess.org/tests/view/60b516c6457376eb8bca9dfa

LTC
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 26200 W: 944 L: 878 D: 24378
Ptnml(0-2): 12, 732, 11545, 800, 11
https://tests.stockfishchess.org/tests/view/60b53652457376eb8bca9e0e

closes https://github.com/official-stockfish/Stockfish/pull/3516

No functional change.
 2021-06-01 21:25:28 +02:00
candirufish
e8418bb1b9 Check Extension with Static Evaluation 
extension for checking moves, at higher depth and more decisive positions.

stc:
LLR: 2.97 (-2.94,2.94) <-0.50,2.50>
Total: 87008 W: 7337 L: 7100 D: 72571
Ptnml(0-2): 264, 5737, 31270, 5964, 269
https://tests.stockfishchess.org/tests/view/60b1034787a1a67ae56c47b6

ltc:
LLR: 2.94 (-2.94,2.94) <0.50,3.50>
Total: 79320 W: 2629 L: 2432 D: 74259
Ptnml(0-2): 29, 2205, 35000, 2392, 34
https://tests.stockfishchess.org/tests/view/60b1ae0b87a1a67ae56c487c

closes https://github.com/official-stockfish/Stockfish/pull/3514

Bench: 4447112
 2021-05-31 18:31:32 +02:00
VoyagerOne
6174a37a37 Remove Stat Reset at beta cutoff 
STC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 63936 W: 5350 L: 5288 D: 53298
Ptnml(0-2): 184, 4295, 22954, 4345, 190
https://tests.stockfishchess.org/tests/view/60affb4c12066fd299795c64

LTC:
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 35856 W: 1201 L: 1142 D: 33513
Ptnml(0-2): 7, 1031, 15795, 1086, 9
https://tests.stockfishchess.org/tests/view/60b0537812066fd299795cc6

closes https://github.com/official-stockfish/Stockfish/pull/3505

bench: 3831936
 2021-05-28 20:16:11 +02:00
Stefan Geschwentner
1b325bf86d Less reduction for capture/promotions. 
Exclude captures/promotions at expected cut nodes (which also not a
former PV node) from LMR if a response to the first previous
opponent move.

STC:
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 288656 W: 24886 L: 24413 D: 239357
Ptnml(0-2): 900, 19738, 102578, 20213, 899
https://tests.stockfishchess.org/tests/view/60ad505112066fd29979595b

LTC:
LLR: 2.97 (-2.94,2.94) <0.50,3.50>
Total: 31344 W: 1107 L: 975 D: 29262
Ptnml(0-2): 12, 879, 13757, 1013, 11
https://tests.stockfishchess.org/tests/view/60adffce12066fd2997959d2

closes https://github.com/official-stockfish/Stockfish/pull/3500

Bench: 3827710
 2021-05-26 17:32:54 +02:00
IIvec
83e0af288a Simplify the thread term for reduction formula 
Dependance on Threads.size() was removed Search::init() for the Reductions[] initialization.

STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 17376 W: 1024 L: 929 D: 15423
Ptnml(0-2): 24, 781, 6989, 864, 30
https://tests.stockfishchess.org/tests/view/60ac110812066fd2997957dc

LTC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 145552 W: 3656 L: 3673 D: 138223
Ptnml(0-2): 37, 3351, 66014, 3340, 34
https://tests.stockfishchess.org/tests/view/60ac267412066fd299795825

closes https://github.com/official-stockfish/Stockfish/pull/3502

Bench 3864295
 2021-05-26 17:25:05 +02:00
bmc4
e044068b43 Increased reduction for captures in LMR 
It now does, in LMR, an increased on reduction by 1 for captures in cut nodes.

STC:
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 30656 W: 2565 L: 2397 D: 25694
Ptnml(0-2): 63, 2012, 11029, 2142, 82
https://tests.stockfishchess.org/tests/view/60a96733ce8ea25a3ef04178

LTC:
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 124840 W: 4139 L: 3878 D: 116823
Ptnml(0-2): 48, 3480, 55100, 3747, 45
https://tests.stockfishchess.org/tests/view/60a995f5ce8ea25a3ef041b7

closes https://github.com/official-stockfish/Stockfish/pull/3494

bench: 3864295
 2021-05-24 15:52:22 +02:00
bmc4
ff4c22238a Tuning Search 
This patch tunes constant in search.cpp

STC:
LLR: 2.94 (-2.94,2.94) <-0.50,2.50>
Total: 30648 W: 2580 L: 2410 D: 25658
Ptnml(0-2): 80, 1969, 11093, 2065, 117
https://tests.stockfishchess.org/tests/view/60a71d3cce8ea25a3ef03fae

LTC:
LLR: 2.95 (-2.94,2.94) <0.50,3.50>
Total: 52896 W: 1776 L: 1617 D: 49503
Ptnml(0-2): 13, 1462, 23347, 1605, 21
https://tests.stockfishchess.org/tests/view/60a794ddce8ea25a3ef0400a

closes https://github.com/official-stockfish/Stockfish/pull/3491

Bench: 4004731
 2021-05-22 19:23:15 +02:00
bmc4
49c79aa15c Simplify reduction for consecutive fails 
Revert the heuristic introduced in #3184, by which we reduced more
the late sons of the root position after consecutive fail highs.

---
Before new net architecture:

STC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 226336 W: 20373 L: 20500 D: 185463
Ptnml(0-2): 755, 16087, 79595, 15992, 739
https://tests.stockfishchess.org/tests/view/609dec205085663412d08e9d

LTC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 67432 W: 2411 L: 2375 D: 62646
Ptnml(0-2): 33, 1944, 29714, 2004, 21
https://tests.stockfishchess.org/tests/view/609ee30f5085663412d08fc3

---
After new net architecture:

STC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 141752 W: 11591 L: 11617 D: 118544
Ptnml(0-2): 387, 9231, 51674, 9189, 395
https://tests.stockfishchess.org/tests/view/60a4320ace8ea25a3ef03cfd

LTC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 294072 W: 9825 L: 9950 D: 274297
Ptnml(0-2): 121, 8610, 129681, 8521, 103
https://tests.stockfishchess.org/tests/view/60a51b5ece8ea25a3ef03dcd
---

closes https://github.com/official-stockfish/Stockfish/pull/3490

Bench: 3752892
 2021-05-22 19:02:36 +02:00
Stéphane Nicolet
754fc8a8b5 Remove Tempo 
The Tempo variable was introduced 10 years ago in our search because the
classical evaluation function was antisymmetrical in White and Black by design
to gain speed:

    Eval(White to play) = -Eval(Black to play)

Nowadays our neural networks know which side is to play in a position when
they evaluate a position and are trained on real games, so the neural network
encodes the advantage of moving as an output of search. This patch shows that
the Tempo variable is not necessary anymore.

STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 33512 W: 2805 L: 2709 D: 27998
Ptnml(0-2): 80, 2209, 12095, 2279, 93
https://tests.stockfishchess.org/tests/view/60a44ceace8ea25a3ef03d30

LTC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 53920 W: 1807 L: 1760 D: 50353
Ptnml(0-2): 16, 1617, 23650, 1658, 19
https://tests.stockfishchess.org/tests/view/60a477f0ce8ea25a3ef03d49

We also tried a match (20000 games) at STC using purely classical, result was neutral:
https://tests.stockfishchess.org/tests/view/60a4eebcce8ea25a3ef03db5

Note: there are two locations left in search.cpp where we assume antisymmetry
of evaluation (in relation with a speed optimization for null moves in lines
770 and 1439), but as the values are just used for heuristic pruning this
approximation should not hurt too much because the order of magnitude is still
true most of the time.

closes https://github.com/official-stockfish/Stockfish/pull/3481

Bench: 4015864
 2021-05-19 20:34:37 +02:00
Vizvezdenec
2c3f7619f9 Simplify usage of LMR for captures 
This patch simplifies a lot of "enablers" for LMR when move is a capture or promotion.
After it we will have only 2 conditions - if node is a cutNode
or if it's an allNode that was not in PV,
so all captures or promotions wouldn't go thru LMR at any PVnodes.

passed STC
https://tests.stockfishchess.org/tests/view/60a40117ce8ea25a3ef03ca7
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 58976 W: 4875 L: 4807 D: 49294
Ptnml(0-2): 176, 3897, 21270, 3973, 172

passed LTC
https://tests.stockfishchess.org/tests/view/60a43ff8ce8ea25a3ef03d18
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 65272 W: 2203 L: 2165 D: 60904
Ptnml(0-2): 28, 1936, 28668, 1978, 26

closes https://github.com/official-stockfish/Stockfish/pull/3480

bench 4110764
 2021-05-19 20:08:51 +02:00
Vizvezdenec
d37de3cb1d Do more continuation history based pruning 
This patch increases lmrDepth threshold for continuation history based pruning in search.
This part of code for a long time was known to be really TC sensitive - decreasing
this threshold easily passed lower time controls but failed badly at LTC,
on the other hand it increase was part of a tuning that resulted
in being negative at STC but was +12 elo at 180+1.8.

After recent simplification of special conditions that sometimes
increase it from 4 to 5 it was logical to overall test at longer
time controls if 5 is better than 4 with deeper searches.

reduces strenght on STC
https://tests.stockfishchess.org/tests/view/60a3a8bbce8ea25a3ef03c74
ELO: -2.57 +-2.0 (95%) LOS: 0.6%
Total: 20000 W: 1820 L: 1968 D: 16212
Ptnml(0-2): 68, 1582, 6836, 1458, 56

Passed LTC with STC bounds
https://tests.stockfishchess.org/tests/view/60a027395085663412d090ce
LLR: 2.93 (-2.94,2.94) <-0.50,2.50>
Total: 175256 W: 6774 L: 6548 D: 161934
Ptnml(0-2): 91, 5808, 75604, 6034, 91

Passed VLTC with LTC bounds
https://tests.stockfishchess.org/tests/view/60a2bccce229097940a037a7
LLR: 2.96 (-2.94,2.94) <0.50,3.50>
Total: 65736 W: 1224 L: 1092 D: 63420
Ptnml(0-2): 5, 1012, 30706, 1136, 9

closes https://github.com/official-stockfish/Stockfish/pull/3473

bench 3689330
 2021-05-19 19:34:37 +02:00
Tomasz Sobczyk
e8d64af123 New NNUE architecture and net 
Introduces a new NNUE network architecture and associated network parameters,
as obtained by a new pytorch trainer.

The network is already very strong at short TC, without regression at longer TC,
and has potential for further improvements.

https://tests.stockfishchess.org/tests/view/60a159c65085663412d0921d
TC: 10s+0.1s, 1 thread
ELO: 21.74 +-3.4 (95%) LOS: 100.0%
Total: 10000 W: 1559 L: 934 D: 7507
Ptnml(0-2): 38, 701, 2972, 1176, 113

https://tests.stockfishchess.org/tests/view/60a187005085663412d0925b
TC: 60s+0.6s, 1 thread
ELO: 5.85 +-1.7 (95%) LOS: 100.0%
Total: 20000 W: 1381 L: 1044 D: 17575
Ptnml(0-2): 27, 885, 7864, 1172, 52

https://tests.stockfishchess.org/tests/view/60a2beede229097940a03806
TC: 20s+0.2s, 8 threads
LLR: 2.93 (-2.94,2.94) <0.50,3.50>
Total: 34272 W: 1610 L: 1452 D: 31210
Ptnml(0-2): 30, 1285, 14350, 1439, 32

https://tests.stockfishchess.org/tests/view/60a2d687e229097940a03c72
TC: 60s+0.6s, 8 threads
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 45544 W: 1262 L: 1214 D: 43068
Ptnml(0-2): 12, 1129, 20442, 1177, 12

The network has been trained (by vondele) using the https://github.com/glinscott/nnue-pytorch/ trainer (started by glinscott),
specifically the branch https://github.com/Sopel97/nnue-pytorch/tree/experiment_56.
The data used are in 64 billion positions (193GB total) generated and scored with the current master net
d8: https://drive.google.com/file/d/1hOOYSDKgOOp38ZmD0N4DV82TOLHzjUiF/view?usp=sharing
d9: https://drive.google.com/file/d/1VlhnHL8f-20AXhGkILujnNXHwy9T-MQw/view?usp=sharing
d10: https://drive.google.com/file/d/1ZC5upzBYMmMj1gMYCkt6rCxQG0GnO3Kk/view?usp=sharing
fishtest_d9: https://drive.google.com/file/d/1GQHt0oNgKaHazwJFTRbXhlCN3FbUedFq/view?usp=sharing

This network also contains a few architectural changes with respect to the current master:

    Size changed from 256x2-32-32-1 to 512x2-16-32-1
        ~15-20% slower
        ~2x larger
        adds a special path for 16 valued ClippedReLU
        fixes affine transform code for 16 inputs/outputs, buy using InputDimensions instead of PaddedInputDimensions
            this is safe now because the inputs are processed in groups of 4 in the current affine transform code
    The feature set changed from HalfKP to HalfKAv2
        Includes information about the kings like HalfKA
        Packs king features better, resulting in 8% size reduction compared to HalfKA
    The board is flipped for the black's perspective, instead of rotated like in the current master
    PSQT values for each feature
        the feature transformer now outputs a part that is fowarded directly to the output and allows learning piece values more directly than the previous network architecture. The effect is visible for high imbalance positions, where the current master network outputs evaluations skewed towards zero.
        8 PSQT values per feature, chosen based on (popcount(pos.pieces()) - 1) / 4
        initialized to classical material values on the start of the training
    8 subnetworks (512x2->16->32->1), chosen based on (popcount(pos.pieces()) - 1) / 4
        only one subnetwork is evaluated for any position, no or marginal speed loss

A diagram of the network is available: https://user-images.githubusercontent.com/8037982/118656988-553a1700-b7eb-11eb-82ef-56a11cbebbf2.png
A more complete description: https://github.com/glinscott/nnue-pytorch/blob/master/docs/nnue.md

closes https://github.com/official-stockfish/Stockfish/pull/3474

Bench: 3806488
 2021-05-18 18:06:23 +02:00
Stéphane Nicolet
f90274d8ce Small clean-ups 
- Comment for Countemove pruning -> Continuation history
- Fix comment in input_slice.h
- Shorter lines in Makefile
- Comment for scale factor
- Fix comment for pinners in see_ge()
- Change Thread.id() signature to size_t
- Trailing space in reprosearch.sh
- Add Douglas Matos Gomes to the AUTHORS file
- Introduce comment for undo_null_move()
- Use Stockfish coding style for export_net()
- Change date in AUTHORS file

closes https://github.com/official-stockfish/Stockfish/pull/3416

No functional change
 2021-05-17 10:47:14 +02:00
Vizvezdenec
61e1c66b7c Simplification for countermoves based pruning 
Simplify away two extra conditions in countermoves based pruning.
These conditions (both of them) were introduced quite a long time ago
via speculative LTCs and seem to no longer bring any benefit.

passed STC
https://tests.stockfishchess.org/tests/view/609e81f35085663412d08f31
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 28488 W: 2487 L: 2382 D: 23619
Ptnml(0-2): 87, 1919, 10123, 2032, 83

passed LTC
https://tests.stockfishchess.org/tests/view/609e9c085085663412d08f59
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 33176 W: 1219 L: 1155 D: 30802
Ptnml(0-2): 13, 1036, 14423, 1106, 10

closes https://github.com/official-stockfish/Stockfish/pull/3468

Bench: 4749514
 2021-05-15 10:29:39 +02:00
bmc4
c82f6f56a6 Simplify LMR rules for statScore 
We simplify two parts of LMR which seem not to bring strength anymore.

---

Individual Tests:
https://tests.stockfishchess.org/tests/view/609d1cc15085663412d0856a
https://tests.stockfishchess.org/tests/view/609cb0cc7746e3dc74ffae8d
https://tests.stockfishchess.org/tests/view/609d1c9f5085663412d08568

---

LTC:
LLR: 2.97 (-2.94,2.94) <-2.50,0.50>
Total: 84184 W: 3093 L: 3066 D: 78025
Ptnml(0-2): 47, 2755, 36458, 2788, 44
https://tests.stockfishchess.org/tests/view/609d84615085663412d08e2f

---

While at it, we also update the Elo estimate of the previous rule in LMR, see:
https://tests.stockfishchess.org/tests/view/609a933c3a33eb67a844f7ca
https://tests.stockfishchess.org/tests/view/609a959c3a33eb67a844f7d5
https://tests.stockfishchess.org/tests/view/609afff73a33eb67a844f870

---

closes https://github.com/official-stockfish/Stockfish/pull/3464

Bench: 4156523
 2021-05-15 10:16:01 +02:00
bmc4
24b8b3098b Remove early return in Probcut code 
We simplify away early return in ProbCut, as it seems not to bring any strength anymore.

STC:
LLR: 2.93 (-2.94,2.94) <-2.50,0.50>
Total: 42632 W: 3705 L: 3617 D: 35310
Ptnml(0-2): 123, 2947, 15110, 2991, 145
https://tests.stockfishchess.org/tests/view/609c49da7746e3dc74ffae02

LTC:
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 35384 W: 1314 L: 1251 D: 32819
Ptnml(0-2): 11, 1130, 15355, 1177, 19
https://tests.stockfishchess.org/tests/view/609c71467746e3dc74ffae47

---

While at it, we also update the Elo estimate of ProbCut
(see https://tests.stockfishchess.org/tests/view/609bfb597746e3dc74ffabe3).

closes https://github.com/official-stockfish/Stockfish/pull/3462

bench: 3764662
 2021-05-15 10:07:40 +02:00
bmc4
594e2ac999 Simplify LMR rule for non-checking captures 
We simplify away the complicated rule in LMR for "non-checking captures
likely to be bad", as it seems not to bring any strength anymore.

STC:
LLR: 2.94 (-2.94,2.94) <-2.50,0.50>
Total: 55256 W: 4972 L: 4897 D: 45387
Ptnml(0-2): 177, 3976, 19234, 4077, 164
https://tests.stockfishchess.org/tests/view/609adf3b3a33eb67a844f842

LTC:
LLR: 2.95 (-2.94,2.94) <-2.50,0.50>
Total: 10344 W: 437 L: 353 D: 9554
Ptnml(0-2): 1, 322, 4449, 392, 8
https://tests.stockfishchess.org/tests/view/609b3dfa3a33eb67a844f88e

--

While at it, we also update the Elo estimate of the previous rule in LMR
(see https://tests.stockfishchess.org/tests/view/609af2a63a33eb67a844f867).

closes https://github.com/official-stockfish/Stockfish/pull/3460

Bench: 3840688
 2021-05-12 17:13:52 +02:00
bmc4
a0e2debe3f Remove coordination between searching threads 
In summary, this revert #2204, as it seems not to bring any strength anymore, so it's no long needed.

STC (5+0.05 @ 8 threads):
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 105728 W: 6406 L: 6393 D: 92929
Ptnml(0-2): 154, 5479, 41599, 5464, 168
https://tests.stockfishchess.org/tests/view/6096994095e7f1852abd3154

LTC (20+0.2 @ 8 threads):
LLR: 2.96 (-2.94,2.94) <-2.50,0.50>
Total: 26336 W: 774 L: 712 D: 24850
Ptnml(0-2): 9, 641, 11810, 695, 13
https://tests.stockfishchess.org/tests/view/6097c62995e7f1852abd31e8

closes https://github.com/official-stockfish/Stockfish/pull/3459

No functional change.
 2021-05-11 19:41:44 +02:00