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Author SHA1 Message Date
mstembera
de24fcebc8 Fix fragile code to use proper random 64 bit keys. 
This fixes an old issue where we want to make a position unique but only
change a small number of bits in the key instead of all 64 of them randomly.
This is fragile and can lead to non uniqueness issues in the TT.

Key make_key(uint64_t seed) takes any integer and produces a unique random 64 bit key.
It is computationally efficient and is based on a congruential pseudo random number
generator using well tested constants by Donald Knuth
(see https://en.wikipedia.org/wiki/Linear_congruential_generator)

STC https://tests.stockfishchess.org/tests/view/5ef6c78f761b685b4c724bb6
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 154320 W: 29343 L: 29376 D: 95601
Ptnml(0-2): 2543, 18170, 35891, 17889, 2667

LTC https://tests.stockfishchess.org/tests/view/5ef7d1a9020eec13834a940e
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 53488 W: 6629 L: 6584 D: 40275
Ptnml(0-2): 372, 4878, 16183, 4955, 356

closes https://github.com/official-stockfish/Stockfish/pull/2773

bench: 4626776
 2020-06-28 21:57:37 +02:00
Joost VandeVondele
ab5cd8340f Small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2756

No functional change
 2020-06-24 22:20:04 +02:00
Vizvezdenec
bbe9857684 Do less futility pruning for captures. 
The idea of this patch is that if capture can be described as
"less valuable piece takes more valuable piece" it's not really correct
to add only piece value of captured piece to static evaluation
since there can be more threats in other places and opponent can't really
do much but recapture our capturing piece which leaves us space for
more captures thus winning more material and increasing static eval.

passed STC
https://tests.stockfishchess.org/tests/view/5ef0167b122d6514328d760f
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 24736 W: 4838 L: 4607 D: 15291
Ptnml(0-2): 438, 2812, 5648, 3021, 449

passed LTC
https://tests.stockfishchess.org/tests/view/5ef073bc122d6514328d7693
LLR: 2.93 (-2.94,2.94) {0.25,1.75}
Total: 46152 W: 5865 L: 5567 D: 34720
Ptnml(0-2): 312, 4160, 13886, 4354, 364

closes https://github.com/official-stockfish/Stockfish/pull/2761

bench 4789930
 2020-06-24 21:56:11 +02:00
Joost VandeVondele
6f15e7fab2 small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2695

No functional change
 2020-06-21 15:22:20 +02:00
Vizvezdenec
bc3c215490 More reduction for evading pawn moves. 
pawn moves are irreversable unlike other evading moves; pawn is the least valuable piece in the game.
So it makes a lot of sence to assume that evading pawn moves are on average not as good as other evading moves thus can be reduced more.

Passed STC
https://tests.stockfishchess.org/tests/view/5ee9602e563bc7aa756002dc
LLR: 2.95 (-2.94,2.94) {-0.50,1.50}
Total: 94176 W: 17993 L: 17668 D: 58515
Ptnml(0-2): 1634, 10742, 21989, 11111, 1612

Passed LTC
https://tests.stockfishchess.org/tests/view/5ee97342563bc7aa75600301
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 20432 W: 2572 L: 2354 D: 15506
Ptnml(0-2): 146, 1707, 6280, 1949, 134

closes https://github.com/official-stockfish/Stockfish/pull/2749

Bench: 5073064
 2020-06-17 07:41:59 +02:00
mstembera
1ea488d34c Use 128 bit multiply for TT index 
Remove super cluster stuff from TT and just use a 128 bit multiply.

STC https://tests.stockfishchess.org/tests/view/5ee719b3aae8aec816ab7548
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 12736 W: 2502 L: 2333 D: 7901
Ptnml(0-2): 191, 1452, 2944, 1559, 222

LTC https://tests.stockfishchess.org/tests/view/5ee732d1aae8aec816ab7556
LLR: 2.93 (-2.94,2.94) {-1.50,0.50}
Total: 27584 W: 3431 L: 3350 D: 20803
Ptnml(0-2): 173, 2500, 8400, 2511, 208

Scheme back to being derived from https://lemire.me/blog/2016/06/27/a-fast-alternative-to-the-modulo-reduction/

Also the default optimized version of the index calculation now uses fewer instructions.
https://godbolt.org/z/Tktxbv
Might benefit from mulx (requires -mbmi2)

closes https://github.com/official-stockfish/Stockfish/pull/2744

bench: 4320954
 2020-06-17 07:32:16 +02:00
xoto10
995ee4b311 Retuned values after eval quantize patch. 
The last search tune patch was tested before the implementation of #2733 which
presumably changed the search characteristics noticeably. Another tuning run was
done, see https://tests.stockfishchess.org/tests/view/5ee5b434ca6c451633a9a08c
and the updated values passed these tests:

STC:
LLR: 2.93 (-2.94,2.94) {-0.50,1.50}
Total: 34352 W: 6600 L: 6360 D: 21392
Ptnml(0-2): 581, 3947, 7914, 4119, 615
https://tests.stockfishchess.org/tests/view/5ee62f05ca6c451633a9a15f

LTC 60+0.6 th 1 :
LLR: 2.97 (-2.94,2.94) {0.25,1.75}
Total: 11176 W: 1499 L: 1304 D: 8373
Ptnml(0-2): 69, 933, 3403, 1100, 83
https://tests.stockfishchess.org/tests/view/5ee6205bca6c451633a9a147

SMP LTC 20+0.2 th 8 :
LLR: 2.93 (-2.94,2.94) {0.25,1.75}
Total: 54032 W: 6126 L: 5826 D: 42080
Ptnml(0-2): 278, 4454, 17280, 4698, 306
https://tests.stockfishchess.org/tests/view/5ee62f25ca6c451633a9a162

Closes https://github.com/official-stockfish/Stockfish/pull/2742

Bench 4957812
 2020-06-15 08:05:16 +02:00
xoto10
42b7dbcb5e Tuned values for search constants 
Tuned search constants after many search patches since the last
successful tune.

1st LTC @ 60+0.6 th 1 :
LLR: 2.97 (-2.94,2.94) {0.25,1.75}
Total: 57656 W: 7369 L: 7036 D: 43251
Ptnml(0-2): 393, 5214, 17336, 5437, 448
https://tests.stockfishchess.org/tests/view/5ee1e074f29b40b0fc95af19

SMP LTC @ 20+0.2 th 8 :
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 83576 W: 9731 L: 9341 D: 64504
Ptnml(0-2): 464, 7062, 26369, 7406, 487
https://tests.stockfishchess.org/tests/view/5ee35a21f29b40b0fc95b008

The changes were rebased on top of a successful patch by Viz (see #2734)
and two different ways of doing this were tested. The successful test
modified the constants in the patch by Viz in a similar manner to the
tuning run:

LTC (rebased) @ 60+0.6 th 1 :
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 193384 W: 24241 L: 23521 D: 145622
Ptnml(0-2): 1309, 17497, 58472, 17993, 1421
https://tests.stockfishchess.org/tests/view/5ee43319ca6c451633a995f9

Further work: the recent patch to quantize eval #2733 affects search quit
quite a bit, so doing another tune in, say, three months time might be a
good idea.

closes https://github.com/official-stockfish/Stockfish/pull/2735

Bench 4246971
 2020-06-13 13:33:18 +02:00
Vizvezdenec
c44c62efc2 Adjust history threshold for quiet moves futility pruning 
This patch adjusts the threshold for futility pruning of quiet moves
using the continuation history array contHist[5], in the same way as
it is used in movepicker.

passed STC:
https://tests.stockfishchess.org/tests/view/5ee3f88bca6c451633a9959f
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 55984 W: 10822 L: 10552 D: 34610
Ptnml(0-2): 952, 6435, 12941, 6719, 945

passed LTC:
https://tests.stockfishchess.org/tests/view/5ee4186dca6c451633a995cf
LLR: 2.96 (-2.94,2.94) {0.25,1.75}
Total: 41712 W: 5402 L: 5114 D: 31196
Ptnml(0-2): 293, 3766, 12469, 4016, 312

closes https://github.com/official-stockfish/Stockfish/pull/2734

Bench: 4715960
 2020-06-13 06:48:58 +02:00
protonspring
1c65310c0e Refactor some threads related code. 
This is a code style change that moves some pure thread code into the threads class.

It is a bit more code, but it makes search.cpp cleaner and easier to read by hiding some thread specific functionality.

STC (SMP)
LLR: 2.93 (-2.94,2.94) {-1.50,0.50}
Total: 75896 W: 12073 L: 12026 D: 51797
Ptnml(0-2): 828, 8224, 19872, 8121, 903
https://tests.stockfishchess.org/tests/view/5ed492e8f29b40b0fc95a74c

closes https://github.com/official-stockfish/Stockfish/pull/2720

No functional change.
 2020-06-09 18:22:27 +02:00
pb00067
15e190e942 Use lowply-history also on low depths 
STC:
https://tests.stockfishchess.org/tests/view/5ed75078f29b40b0fc95a8b9
LLR: 2.93 (-2.94,2.94) {-0.50,1.50}
Total: 73928 W: 14301 L: 14005 D: 45622
Ptnml(0-2): 1243, 8572, 17096, 8752, 1301

LTC:
https://tests.stockfishchess.org/tests/view/5ed895e0f29b40b0fc95a976
LLR: 2.93 (-2.94,2.94) {0.25,1.75}
Total: 154848 W: 19684 L: 19074 D: 116090
Ptnml(0-2): 1048, 14108, 46627, 14468, 1173

closes https://github.com/official-stockfish/Stockfish/pull/2718

bench: 4582693
 2020-06-06 16:18:42 +02:00
Moez Jellouli
784263596f Minimal thinking time, even if only one rootMove. 
without search, the eval returned can be misleading (e.g. mate instead of draw),
leading to wrong adjudication. With a minimal search, this is avoided.
This patch leads to 1ms long searches if there is only 1 move,
similar patches all indicate a small Elo gain.

Fixes https://github.com/official-stockfish/Stockfish/issues/2707

Passed non-regression STC:
LLR: 2.93 (-2.94,2.94) {-1.50,0.50}
Total: 22312 W: 4350 L: 4204 D: 13758
Ptnml(0-2): 323, 2488, 5437, 2536, 372
https://tests.stockfishchess.org/tests/view/5ed562b0f29b40b0fc95a7d0

closes https://github.com/official-stockfish/Stockfish/pull/2709

Bench: 4733799
 2020-06-06 15:58:50 +02:00
Moez Jellouli
16566a8fcf Singular quiet LMR 
If ttMove is a capture and had a singular extension, it is probably the best move.
No need to make a decrease of LMR on other moves.

STC
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 41968 W: 8170 L: 7918 D: 25880
Ptnml(0-2): 733, 4770, 9726, 5022, 733
https://tests.stockfishchess.org/tests/view/5ed6b666f29b40b0fc95a884

LTC
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 71376 W: 9200 L: 8827 D: 53349
Ptnml(0-2): 486, 6544, 21342, 6743, 573
https://tests.stockfishchess.org/tests/view/5ed7578bf29b40b0fc95a8c9

closes https://github.com/official-stockfish/Stockfish/pull/2713

Bench: 4733799
 2020-06-04 19:03:54 +02:00
Joost VandeVondele
616eb60008 Less pruning in draw PV lines. 
no futility pruning for certain captures if the PvNode has a draw eval.

passed STC:
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 59392 W: 11576 L: 11302 D: 36514
Ptnml(0-2): 977, 6816, 13920, 6922, 1061
https://tests.stockfishchess.org/tests/view/5ed0b1bb042fa6d77c355295

passed LTC:
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 64040 W: 8273 L: 7923 D: 47844
Ptnml(0-2): 424, 5842, 19220, 6028, 506
https://tests.stockfishchess.org/tests/view/5ed145e0042fa6d77c35531c

closes https://github.com/official-stockfish/Stockfish/pull/2705

Bench: 4704615
 2020-05-30 20:32:52 +02:00
Joost VandeVondele
383b12e1a5 small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2653

No functional change
 2020-05-23 13:27:16 +02:00
xoto10
d940e59dad Keep low ply history from previous move 
This patch keeps the low-ply history from the previous move, shifting the data down by 2 ply.

Tested with closedpos book:

STC:
LLR: 2.93 (-2.94,2.94) {-0.50,1.50}
Total: 71584 W: 14175 L: 13891 D: 43518
Ptnml(0-2): 1069, 8228, 16993, 8354, 1148
https://tests.stockfishchess.org/tests/view/5ec0eaafe9d85f94dc429974

LTC:
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 96552 W: 13946 L: 13498 D: 69108
Ptnml(0-2): 676, 9082, 28375, 9404, 739
https://tests.stockfishchess.org/tests/view/5ec145efe9d85f94dc4299b0

closes https://github.com/official-stockfish/Stockfish/pull/2688

Bench 5148950
 2020-05-23 13:19:26 +02:00
Joost VandeVondele
353e20674b Small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2628

No functional change
 2020-04-29 17:44:24 +02:00
Vizvezdenec
4776dc0e12 Introduce futility pruning for captures 
The idea is somewhat similar to futility pruning for quiet moves -
if a late enough capture doesn't give check and the static eval is
much lower than alpha we can almost safely assume that this capture
wouldn't be a good move.

passed STC
https://tests.stockfishchess.org/tests/view/5ea8544b53a4548a0348ee5b
LLR: 2.95 (-2.94,2.94) {-0.50,1.50}
Total: 236040 W: 44420 L: 43894 D: 147726
Ptnml(0-2): 3830, 27202, 55496, 27596, 3896

passed LTC
https://tests.stockfishchess.org/tests/view/5ea87c842141237a731f0c7d
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 81336 W: 10429 L: 10028 D: 60879
Ptnml(0-2): 589, 7356, 24404, 7703, 616

closes https://github.com/official-stockfish/Stockfish/pull/2651

bench 4405247
 2020-04-29 17:35:48 +02:00
pb00067
bb5589b829 continuation histories when in check 
If in check, don't write to continuation histories ss-4, ss-6.
Adding inCheck to the stack was needed, and might be useful for
future patches.

Passed STC:
https://tests.stockfishchess.org/tests/view/5e9ee24acaaff5d60a50b812
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 61774 W: 11725 L: 11449 D: 38600
Ptnml(0-2): 971, 7211, 14322, 7337, 1046

Passed LTC:
https://tests.stockfishchess.org/tests/view/5e9eecb7caaff5d60a50b831
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 250822 W: 32067 L: 31179 D: 187576
Ptnml(0-2): 1745, 23126, 74824, 23928, 1788

closes https://github.com/official-stockfish/Stockfish/pull/2645

bench: 4808463
 2020-04-22 08:48:01 +02:00
Vizvezdenec
221893bf67 Apply multicut pruning more often 
This patch increases number of nodes where we produce multicut cutoffs.

The idea is that if our ttMove failed to produce a singular extension
but ttValue is greater than beta we can afford to do one more reduced search
near beta excluding ttMove to see if it will produce a fail high -
and if it does so produce muticut by analogy to existing logic.

passed STC
https://tests.stockfishchess.org/tests/view/5e9a162b5b664cdba0ce6e28
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 58238 W: 11192 L: 10917 D: 36129
Ptnml(0-2): 1007, 6704, 13442, 6939, 1027

passed LTC
https://tests.stockfishchess.org/tests/view/5e9a1e845b664cdba0ce7411
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 137852 W: 17460 L: 16899 D: 103493
Ptnml(0-2): 916, 12610, 41383, 13031, 986

closes https://github.com/official-stockfish/Stockfish/pull/2640

bench 4881443
 2020-04-18 15:36:41 +02:00
Joost VandeVondele
345b2d153a Remove one condition in probcut TTmove skipping 
the removed condition appears illogical and is not needed.

passed STC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 80418 W: 15217 L: 15144 D: 50057
Ptnml(0-2): 1341, 9399, 18679, 9426, 1364
https://tests.stockfishchess.org/tests/view/5e977eb5c9ada107a0370d6b

passed LTC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 49878 W: 6299 L: 6247 D: 37332
Ptnml(0-2): 327, 4677, 14897, 4693, 345
https://tests.stockfishchess.org/tests/view/5e97e07dc9ada107a0370e53

closes https://github.com/official-stockfish/Stockfish/pull/2638

Bench: 4958027
 2020-04-16 21:44:52 +02:00
Vizvezdenec
0e51ff1074 Don't attempt probcut if ttMove is not good enough. 
This idea is loosely based on xoroshiro idea about raisedBeta and ttmoves.
If our ttmove have low enough ttvalue and is deep enough (deeper than our probcut depth) it makes little sense to try probcut moves, since the ttMove already more or less failed to produce one according to transposition table.

passed STC
https://tests.stockfishchess.org/tests/view/5e9673ddc2718dee3c822920
LLR: 2.95 (-2.94,2.94) {-0.50,1.50}
Total: 72148 W: 14038 L: 13741 D: 44369
Ptnml(0-2): 1274, 8326, 16615, 8547, 1312

passed LTC
https://tests.stockfishchess.org/tests/view/5e96b378c2718dee3c8229bf
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 89054 W: 11418 L: 10996 D: 66640
Ptnml(0-2): 623, 8113, 26643, 8515, 633

closes https://github.com/official-stockfish/Stockfish/pull/2632

bench 4952731
 2020-04-15 20:33:03 +02:00
silversolver1
de9fc53af5 Removes evasionPrunable 
STC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 25656 W: 4979 L: 4826 D: 15851
Ptnml(0-2): 414, 2971, 5964, 3006, 473
https://tests.stockfishchess.org/tests/view/5e93dbd72cb65b3059c33819

LTC:
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 43732 W: 5656 L: 5593 D: 32483
Ptnml(0-2): 324, 4072, 13009, 4139, 322
https://tests.stockfishchess.org/tests/view/5e93e37c2cb65b3059c33825

closes https://github.com/official-stockfish/Stockfish/pull/2627

Bench: 4702195
 2020-04-13 09:20:53 +02:00
Joost VandeVondele
2c5f0efa13 Extend irreversible moves 
if these are ttMoves and played in positions with a high value of the rule50 counter. The unusual extension of 2 is safe in this context as awarding it will reset the rule50 counter, making sure it is awarded very rarely in a search path.

This patch partially addresses https://github.com/official-stockfish/Stockfish/issues/2620 as it should make it less likely to play a move that resets the counter, but that is worse than alternative moves after a slightly deeper search.

passed STC:
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 71658 W: 13840 L: 13560 D: 44258
Ptnml(0-2): 1058, 7921, 17643, 8097, 1110
https://tests.stockfishchess.org/tests/view/5e90d0f6754c3424c4cf9f41

passed LTC:
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 85082 W: 11069 L: 10680 D: 63333
Ptnml(0-2): 459, 6982, 27259, 7393, 448
https://tests.stockfishchess.org/tests/view/5e917470af0a0143109dc341

closes https://github.com/official-stockfish/Stockfish/pull/2623

Bench: 4432822
 2020-04-12 20:38:47 +02:00
Joost VandeVondele
f83cb95740 Small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2606

No functional change
 2020-04-12 20:30:08 +02:00
Vizvezdenec
195a4fec6d Introduce capture history pruning 
This patch introduces a heuristic that is similar to countermove based pruning but for captures - capture history pruning. The idea is that we can (almost) safely prune really late captures with negative history if they don't give check so will most likely not produce some king-attacking tactic.

passed STC
https://tests.stockfishchess.org/tests/view/5e8c60d40ffd2be7f15e5470
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 23748 W: 4758 L: 4529 D: 14461
Ptnml(0-2): 421, 2712, 5400, 2899, 442

passed LTC
https://tests.stockfishchess.org/tests/view/5e8c72bf0ffd2be7f15e547f
LLR: 2.96 (-2.94,2.94) {0.25,1.75}
Total: 17330 W: 2415 L: 2190 D: 12725
Ptnml(0-2): 126, 1561, 5107, 1704, 167

closes https://github.com/official-stockfish/Stockfish/pull/2618

bench 4417023
 2020-04-07 17:47:01 +02:00
Vizvezdenec
85bcf4741e Further increase reductions with increasing number of threads 
This patch doubles the reduction increase with thread count.

passed STC
https://tests.stockfishchess.org/tests/view/5e874f5a4411759d9d098696
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 9162 W: 1558 L: 1385 D: 6219
Ptnml(0-2): 90, 958, 2343, 1069, 121

passed LTC
https://tests.stockfishchess.org/tests/view/5e8762804411759d9d09869f
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 79364 W: 9541 L: 9159 D: 60664
Ptnml(0-2): 462, 6880, 24661, 7172, 507

closes https://github.com/official-stockfish/Stockfish/pull/2615

bench 4831963
 2020-04-05 08:44:25 +02:00
Vizvezdenec
c14f4877cf Increase reduction for captures. 
The idea behind this patch is that if static eval is really bad so capturing of current piece on spot will still produce a position with an eval much lower than alpha then our best chance is to create some kind of king attack. So captures without check are mostly worse than captures with check and can be reduced more.

passed STC
https://tests.stockfishchess.org/tests/view/5e8514b44411759d9d098543
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 46196 W: 9039 L: 8781 D: 28376
Ptnml(0-2): 750, 5412, 10628, 5446, 862

passed LTC
https://tests.stockfishchess.org/tests/view/5e8530134411759d9d09854c
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 23462 W: 3228 L: 2988 D: 17246
Ptnml(0-2): 186, 2125, 6849, 2405, 166

close https://github.com/official-stockfish/Stockfish/pull/2612

bench 4742598
 2020-04-02 15:11:16 +02:00
mstembera
84f3bf594d No voting for TB loss / mate. 
Just as we pick the shortest mate also make sure we stave off mate as long as possible.

https://github.com/official-stockfish/Stockfish/pull/2603

bench: 5138771
 2020-04-02 14:54:47 +02:00
Joost VandeVondele
209e94203f Small cleanups 
https://github.com/official-stockfish/Stockfish/pull/2584

No functional change.
 2020-03-30 22:46:07 +02:00
Praveen tummala
b7ecdaada7 Movecount pruning reduction logic 
This patch refines search reduction logic in case the position is not a former PV node and is pruned based on move count.

passed STC
https://tests.stockfishchess.org/tests/view/5e8092bde42a5c3b3ca2ed35
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 78848 W: 15480 L: 15170 D: 48198
Ptnml(0-2): 1406, 9310, 17773, 9438, 1497

passed LTC
https://tests.stockfishchess.org/tests/view/5e80bb13e42a5c3b3ca2ed4b
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 86596 W: 11451 L: 11033 D: 64112
Ptnml(0-2): 624, 7993, 25687, 8329, 665

closes https://github.com/official-stockfish/Stockfish/pull/2605

Bench: 5138771
 2020-03-30 22:41:22 +02:00
xoto10
8c73339a36 Remove previousScore adjustment of delta. 
STC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 14580 W: 2904 L: 2731 D: 8945
Ptnml(0-2): 243, 1665, 3339, 1762, 281
https://tests.stockfishchess.org/tests/view/5e7d080ae42a5c3b3ca2ebc6

LTC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 60338 W: 7870 L: 7831 D: 44637
Ptnml(0-2): 451, 5596, 18018, 5671, 433
https://tests.stockfishchess.org/tests/view/5e7d11b3e42a5c3b3ca2ebd3

closes https://github.com/official-stockfish/Stockfish/pull/2598

Bench 5247262
 2020-03-29 19:44:07 +02:00
Lyudmil Antonov
58746d9fb8 Tuned history reduction 
Value after a long Bayesian tuning, using a home-made classification approach.

STC
https://tests.stockfishchess.org/tests/view/5e7c7b16e42a5c3b3ca2eb66
LLR: 2.96 (-2.94,2.94) {-0.50,1.50}
Total: 45472 W: 8992 L: 8732 D: 27748
Ptnml(0-2): 795, 5276, 10352, 5500, 813

LTC
https://tests.stockfishchess.org/tests/view/5e7c8be7e42a5c3b3ca2eb75
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 22744 W: 3085 L: 2849 D: 16810
Ptnml(0-2): 156, 2090, 6658, 2298, 170

closes https://github.com/official-stockfish/Stockfish/pull/2597

Bench 5030855
 2020-03-26 17:49:28 +01:00
Vizvezdenec
6ecab03dee Adjust singular extension search depth 
This patch applies a different singular extension search logic in case the position is ttPv && !PvNode.
It changes the depth of this search, higher for this types of nodes, and lower for other nodes.

passed STC
http://tests.stockfishchess.org/tests/view/5e72bbaae42a5c3b3ca2e75e
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 12692 W: 2608 L: 2389 D: 7695
Ptnml(0-2): 238, 1414, 2839, 1601, 254

passed LTC
http://tests.stockfishchess.org/tests/view/5e731c07e42a5c3b3ca2e770
LLR: 2.96 (-2.94,2.94) {0.25,1.75}
Total: 145716 W: 19218 L: 18626 D: 107872
Ptnml(0-2): 1100, 13605, 42899, 14111, 1143

closes https://github.com/official-stockfish/Stockfish/pull/2590

Bench: 5398277
 2020-03-20 21:07:37 +01:00
Vizvezdenec
ff27109313 Adjust singular LMR for positions seen in PV 
This patch continues work on altering search for ttPv nodes, using recent idea to alter it more in not PvNodes. Previous tweak based on this idea adjusted singularBeta - this one adjusts value of singularLMR, so they are both related to singular extension search.

passed STC
http://tests.stockfishchess.org/tests/view/5e700737e42a5c3b3ca2e659
LLR: 2.95 (-2.94,2.94) {-0.50,1.50}
Total: 140608 W: 27053 L: 26659 D: 86896
Ptnml(0-2): 2425, 16337, 32439, 16625, 2478

passed LTC
http://tests.stockfishchess.org/tests/view/5e7068eae42a5c3b3ca2e687
LLR: 2.94 (-2.94,2.94) {0.25,1.75}
Total: 79318 W: 10463 L: 10064 D: 58791
Ptnml(0-2): 567, 7416, 23359, 7685, 632

closes https://github.com/official-stockfish/Stockfish/pull/2588

Bench: 4952322
 2020-03-17 19:34:47 +01:00
Joost VandeVondele
ddcbacd04d Small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2567

No functional change.
 2020-03-14 17:04:50 +01:00
pb00067
ec2002c594 Simplify futility pruning parent node 
only continuation histories seem needed for this purpose.

STC:
http://tests.stockfishchess.org/tests/view/5e6b88dfe42a5c3b3ca2e4ab
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 113356 W: 21725 L: 21696 D: 69935
Ptnml(0-2): 1999, 13255, 26163, 13240, 2021

LTC:
http://tests.stockfishchess.org/tests/view/5e6babbfe42a5c3b3ca2e4c2
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 22164 W: 2917 L: 2821 D: 16426
Ptnml(0-2): 173, 2040, 6548, 2160, 161

closes https://github.com/official-stockfish/Stockfish/pull/2583

bench: 4839496
 2020-03-14 16:30:17 +01:00
silversolver1
c077bfb413 Remove set statScore to zero 
Simplification. Removes setting statScore to zero if negative.

STC:
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 84820 W: 16100 L: 16033 D: 52687
Ptnml(0-2): 1442, 9865, 19723, 9944, 1436
https://tests.stockfishchess.org/tests/view/5e654fdae42a5c3b3ca2e2f8

LTC:
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 57658 W: 7435 L: 7391 D: 42832
Ptnml(0-2): 441, 5397, 17104, 5451, 436
https://tests.stockfishchess.org/tests/view/5e657ce9e42a5c3b3ca2e307

closes https://github.com/official-stockfish/Stockfish/pull/2578

Bench: 5168890
 2020-03-09 22:46:13 +01:00
Gary Heckman
37e3863927 Fix ambiguity between clamp implementations 
There is an ambiguity between global and std clamp implementations when compiling in c++17,
and on certain toolchains that are not strictly conforming to c++11.
This is solved by putting our clamp implementation in a namespace.

closes https://github.com/official-stockfish/Stockfish/pull/2572

No functional change.
 2020-03-07 11:14:27 +01:00
Joost VandeVondele
c6839a2615 Small cleanups 
closes https://github.com/official-stockfish/Stockfish/pull/2546

No functional change.
 2020-03-01 09:31:58 +01:00
Guenther Demetz
f27339d35b Simplify lowply-history logic 
Don't restrict usage to ttPv nodes exclusively

STC:
http://tests.stockfishchess.org/tests/view/5e5634f284a82b4acd41499a
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 152796 W: 29146 L: 29178 D: 94472
Ptnml(0-2): 2590, 17792, 35628, 17836, 2552

LTC:
http://tests.stockfishchess.org/tests/view/5e575d4984a82b4acd4149e8
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 20078 W: 2688 L: 2587 D: 14803
Ptnml(0-2): 139, 1914, 5853, 1973, 160

closes https://github.com/official-stockfish/Stockfish/pull/2565

bench: 4923286
 2020-03-01 09:20:31 +01:00
AndyGrant
2e1369d030 Fix TT write in MultiPV case. 
fixes an error reported earlier as https://github.com/official-stockfish/Stockfish/issues/2404 by @AndyGrant.

MultiPV at root shouldn't write to the TT for later lines, as that is neither the eval nor the bestmove for that position.
Fixing this error doesn't matter for playing games (http://tests.stockfishchess.org/tests/view/5dcdbd810ebc590256324a11).

However, it can lead to wrong mate announcements as reported by @uriblass. In particular the following testcase gives
wrong results for the second search, prior to this patch:

```
setoption name MultiPV value 2
position fen 5R2/2kB2p1/p2bR3/8/3p1B2/8/PPP5/2K5 b - - 0 49
go depth 40
position fen 2B2R2/3r2p1/p1kbR3/8/3p1B2/8/PPP5/2K5 b - - 8 48
go depth 40
```

fixes https://github.com/official-stockfish/Stockfish/issues/2561
closes https://github.com/official-stockfish/Stockfish/pull/2562

Only affects MultiPV search.

Bench: 4697493
 2020-02-25 21:10:10 +01:00
Günther Demetz
b8c00efa27 Improve move order near the root 
Current move histories are known to work well near the leaves, whilst at
higher depths they aren't very helpful. To address this problem this
patch introduces a table dedicated for what's happening at plies 0-3.
It's structured like mainHistory with ply index instead of color.
It get cleared with each new search and is filled during iterative
deepening at higher depths when recording successful quiet moves near
the root or traversing nodes which were in the principal variation
(ttPv).

Medium TC (20+0.2):
https://tests.stockfishchess.org/tests/view/5e4d358790a0a02810d096dc
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 100910 W: 16682 L: 16376 D: 67852
Ptnml(0-2): 1177, 10983, 25883, 11181, 1231

LTC:
https://tests.stockfishchess.org/tests/view/5e4e2cb790a0a02810d09714
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 80444 W: 10495 L: 10095 D: 59854
Ptnml(0-2): 551, 7479, 23803, 7797, 592

closes https://github.com/official-stockfish/Stockfish/pull/2557

Bench: 4705960
 2020-02-22 21:32:32 +01:00
protonspring
10ead8a724 Simplify Futility Move Count 
remove two constants

STC
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 62050 W: 11903 L: 11802 D: 38345
Ptnml(0-2): 1002, 7346, 14283, 7320, 1065
http://tests.stockfishchess.org/tests/view/5e41d73be70d848499f63c6d

LTC
LLR: 2.93 (-2.94,2.94) {-1.50,0.50}
Total: 12850 W: 1679 L: 1572 D: 9599
Ptnml(0-2): 82, 1171, 3818, 1249, 96
http://tests.stockfishchess.org/tests/view/5e42bf07e70d848499f63cc0

Bench: 4762351
 2020-02-15 15:13:14 +01:00
Joost VandeVondele
be5a2f015e Fix for incorrect VALUE_MATE_IN_MAX_PLY usage. 
Fixes #2533, fixes #2543, fixes #2423.

the code that prevents false mate announcements depending on the TT
state (GHI), incorrectly used VALUE_MATE_IN_MAX_PLY. The latter
constant, however, also includes, counterintuitively, the TB win range.

This patch fixes that, by restoring the behavior for TB win scores,
while retaining the false mate correctness, and improving the mate
finding ability. In particular

no alse mates are announced with the poisened hash testcase
```
position fen 8/8/8/3k4/8/8/6K1/7R w - - 0 1
go depth 40
position fen 8/8/8/3k4/8/8/6K1/7R w - - 76 1
go depth 20
ucinewgame
```

mates are found with the testcases reported in #2543
```
position fen 4k3/3pp3/8/8/8/8/2PPP3/4K3 w - - 0 1
setoption name Hash value 1024
go depth 55
ucinewgame
```
and
```
position fen 4k3/4p3/8/8/8/8/3PP3/4K3 w - - 0 1
setoption name Hash value 1024
go depth 45
ucinewgame
```

furthermore, on the mate finding benchmark (ChestUCI_23102018.epd),
performance improves over master, roughly reaching performance with the
false mate protection reverted
```
Analyzing 6566 mate positions for best and found mates:

                 ----------------best ---------------found
           nodes master revert  fixed master revert  fixed
        16000000   4233   4236   4235   5200   5201   5199
        32000000   4583   4585   4585   5417   5424   5418
        64000000   4852   4853   4855   5575   5584   5579
       128000000   5071   5068   5066   5710   5720   5716
       256000000   5280   5282   5279   5819   5827   5826
       512000000   5471   5468   5468   5919   5935   5932
```

On a testcase with TB enabled, progress is made consistently, contrary
to master
```
setoption name SyzygyPath value ../../../syzygy/3-4-5/
setoption name Hash value 2048
position fen 1R6/3k4/8/K2p4/4n3/2P5/8/8 w - - 0 1
go depth 58
ucinewgame
```

The PR (prior to a rewrite for clarity)

passed STC:
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 65405 W: 12454 L: 12384 D: 40567
Ptnml(0-2): 920, 7256, 16285, 7286, 944
http://tests.stockfishchess.org/tests/view/5e441a3be70d848499f63d15

passed LTC:
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 27096 W: 3477 L: 3413 D: 20206
Ptnml(0-2): 128, 2215, 8776, 2292, 122
http://tests.stockfishchess.org/tests/view/5e44e277e70d848499f63d63

The incorrectly named VALUE_MATE_IN_MAX_PLY and VALUE_MATED_IN_MAX_PLY
were renamed into VALUE_TB_WIN_IN_MAX_PLY and VALUE_TB_LOSS_IN_MAX_PLY,
and correclty defined VALUE_MATE_IN_MAX_PLY and VALUE_MATED_IN_MAX_PLY
were introduced.

One further (corner case) mistake using these constants was fixed (go
mate X), which could lead to a premature return if X > MAX_PLY / 2,
but TB were present.

Thanks to @svivanov72 for one of the reports and help fixing the issue.

closes https://github.com/official-stockfish/Stockfish/pull/2552

Bench: 4932981
 2020-02-15 15:10:07 +01:00
Vizvezdenec
4e8986483a Modify singular beta for ttPv positions. 
This patch lowers singular beta for positions that have been in pv and are not pv nodes.
The idea of using ttpv && !PvNode improved scaling with TC and could be
useful for other search heuristics.

passed STC
http://tests.stockfishchess.org/tests/view/5e3f6d7ce70d848499f63bbc
LLR: 2.94 (-2.94,2.94) {-0.50,1.50}
Total: 154953 W: 29688 L: 29272 D: 95993
Ptnml(0-2): 2616, 17912, 36037, 18210, 2673

passed LTC
http://tests.stockfishchess.org/tests/view/5e405561e70d848499f63bfa
LLR: 2.95 (-2.94,2.94) {0.25,1.75}
Total: 70974 W: 9305 L: 8932 D: 52737
Ptnml(0-2): 466, 6658, 20920, 6826, 569

closes https://github.com/official-stockfish/Stockfish/pull/2550

Bench: 4932981
 2020-02-10 09:19:02 +01:00
xoto10
c390b734c4 Simplify Tweak late move reductions at root. 
Revert change from Jan 15.

STC 10+0.1 :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 65135 W: 12543 L: 12436 D: 40156
Ptnml(0-2): 1090, 7618, 14947, 7623, 1136
https://tests.stockfishchess.org/tests/view/5e334016708b13464ceea32e

LTC 60+0.6 :
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 17768 W: 2286 L: 2191 D: 13291
Ptnml(0-2): 128, 1602, 5273, 1679, 140
https://tests.stockfishchess.org/tests/view/5e34011e57e1ecae66ec2aab

closes https://github.com/official-stockfish/Stockfish/pull/2537

Bench: 4914050
 2020-02-01 09:05:13 +01:00
Joost VandeVondele
6ccb1cac5a Revert 5 recent patches 
Revert 5 patches which were merged, but lead to a regression test that showed negative Elo gain:

http://tests.stockfishchess.org/tests/view/5e307251ab2d69d58394fdb9

This was discussed in depth in:

https://github.com/official-stockfish/Stockfish/issues/2531

Each patch was removed and tested as a simplification, full list below, and the whole combo as well.

After the revert the regression test showed a neutral result:

http://tests.stockfishchess.org/tests/view/5e334851708b13464ceea33c

As a result of this experience, the SPRT testing bounds will be made more strict.

Reverted patches:

1 Dynamic Complexity 6d0eabd5fe :

STC 10+0.1 https://tests.stockfishchess.org/tests/view/5e31fcacec661e2e6a340d08 :
LLR: 2.97 (-2.94,2.94) {-1.50,0.50}
Total: 38130 W: 7326 L: 7189 D: 23615
Ptnml(0-2): 677, 4346, 8843, 4545, 646

LTC 60+0.6 https://tests.stockfishchess.org/tests/view/5e32c18fec661e2e6a340d73 :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 38675 W: 4941 L: 4866 D: 28868
Ptnml(0-2): 270, 3556, 11429, 3584, 291

3 More bonus for bestMoves on past PV nodes 71e0b5385e :

STC 10+0.1 https://tests.stockfishchess.org/tests/view/5e31fe93ec661e2e6a340d10 :
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 46100 W: 8853 L: 8727 D: 28520
Ptnml(0-2): 796, 5297, 10749, 5387, 813

LTC 60+0.6 https://tests.stockfishchess.org/tests/view/5e32c187ec661e2e6a340d71 :
LLR: 2.96 (-2.94,2.94) {-1.50,0.50}
Total: 16920 W: 2161 L: 2055 D: 12704
Ptnml(0-2): 115, 1498, 5006, 1569, 130

4 Tweak Restricted Piece Bonus 0ae00454ba :

STC 10+0.1 https://tests.stockfishchess.org/tests/view/5e31fefaec661e2e6a340d15 :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 88328 W: 17060 L: 16997 D: 54271
Ptnml(0-2): 1536, 10446, 20169, 10422, 1581

LTC 60+0.6 https://tests.stockfishchess.org/tests/view/5e32c17aec661e2e6a340d6f :
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 34784 W: 4551 L: 4466 D: 25767
Ptnml(0-2): 255, 3279, 10061, 3345, 262

5 History update for pruned captures 01b6088af3 :

STC 10+0.1 https://tests.stockfishchess.org/tests/view/5e31ff5eec661e2e6a340d1a :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 29541 W: 5735 L: 5588 D: 18218
Ptnml(0-2): 483, 3445, 6820, 3469, 545

LTC 60+0.6 https://tests.stockfishchess.org/tests/view/5e32c196ec661e2e6a340d75 :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 22177 W: 2854 L: 2757 D: 16566
Ptnml(0-2): 143, 2005, 6555, 2055, 164

6 Tweak trapped rook penalty 18fc21eba0 :

STC 10+0.1 https://tests.stockfishchess.org/tests/view/5e31ffb1ec661e2e6a340d1c :
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 24476 W: 4727 L: 4569 D: 15180
Ptnml(0-2): 390, 2834, 5659, 2933, 417

LTC 60+0.6 https://tests.stockfishchess.org/tests/view/5e32c19eec661e2e6a340d77 :
LLR: 2.95 (-2.94,2.94) {-1.50,0.50}
Total: 97332 W: 12492 L: 12466 D: 72374
Ptnml(0-2): 690, 9107, 28738, 9034, 720

All 5 as one simplification :
LTC 60+0.6 https://tests.stockfishchess.org/tests/view/5e334098708b13464ceea330 :
LLR: 2.94 (-2.94,2.94) {-1.50,0.50}
Total: 7829 W: 1079 L: 964 D: 5786
Ptnml(0-2): 52, 690, 2281, 781, 65

Bench: 5153165
 2020-01-31 19:48:44 +01:00
Guenther Demetz
71e0b5385e More bonus for bestMoves on past PV nodes 
It looks like it is important to keep past PV (ttPv) nodes as close as possible to current PV nodes.
Credits to Mark Tenzer (31m059) & Stefan Geschwentner who first tried ideas on ttPv nodes.

STC:
https://tests.stockfishchess.org/tests/view/5e2ff5efab2d69d58394fd52
LLR: 2.95 (-2.94,2.94) {-1.00,3.00}
Total: 13302 W: 2647 L: 2507 D: 8148
Ptnml(0-2): 237, 1540, 2956, 1632, 260

LTC:
https://tests.stockfishchess.org/tests/view/5e2fff38ab2d69d58394fd55
LLR: 2.95 (-2.94,2.94) {0.00,2.00}
Total: 15797 W: 2137 L: 1960 D: 11700
Ptnml(0-2): 96, 1443, 4628, 1547, 130

closes https://github.com/official-stockfish/Stockfish/pull/2529

bench: 5545845
 2020-01-28 16:28:56 +01:00
31m059
d878bc8cda Less NMP if the position was previously in PV. 
The intention of the patch is to avoid aggressive null move pruning (NMP)
in positions that have previously been found to be important (PV nodes).
If we already do not apply NMP for current PV nodes, it makes sense to apply
it less often for positions that have previously been PV nodes too.

STC:
LLR: 2.96 (-2.94,2.94) {-1.00,3.00}
Total: 14959 W: 2921 L: 2782 D: 9256
Ptnml(0-2): 254, 1679, 3493, 1762, 282
http://tests.stockfishchess.org/tests/view/5e2f6637ab2d69d58394fcfd

LTC:
LLR: 2.95 (-2.94,2.94) {0.00,2.00}
Total: 6442 W: 899 L: 753 D: 4790
Ptnml(0-2): 42, 549, 1885, 659, 61
http://tests.stockfishchess.org/tests/view/5e2f767bab2d69d58394fd04

closes https://github.com/official-stockfish/Stockfish/pull/2525

Bench: 4725546
 2020-01-28 10:31:25 +01:00