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Author SHA1 Message Date
Stefan GeschwentnerandStéphane Nicolet 1725ed39ad Tweak dynamic contempt (the birthday patch) 
Make dynamic contempt weight factor dependent on static contempt so that higher
static contempt implies less dynamic contempt and vice versa. For default contempt
24 this is a non-functional change. But tests with contempt 0 shows an elo gain.
Also today is my birthday so i have already give to myself a gift with this patch :-)!

Further proceedings:

in the past we checked for default contempt that it doesn't regress against
contempt 0. Now that the later is stronger and the former is the same strength
this should be rechecked. Perhaps the default contempt have to be lowered.
It would be interesting to get some idea of the impact of this patch outside
of the 0-24 contempt range.

STC: (both with contempt=0)
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 21912 W: 3898 L: 3740 D: 14274
http://tests.stockfishchess.org/tests/view/5db74b6f0ebc5902d1f37405

LTC: (both with contempt=0)
LLR: 2.96 (-2.94,2.94) [0.00,3.50]
Total: 27172 W: 3350 L: 3126 D: 20696
http://tests.stockfishchess.org/tests/view/5db760020ebc5902d1f375d0

Closes https://github.com/official-stockfish/Stockfish/pull/2382

No functional change (for current default contempt 24).
 2019-10-31 17:05:29 +01:00
Stefan GeschwentnerandStéphane Nicolet 61f44ce578 Update reverse move stats 
For a good quiet non-pawn move consider the reverse move as bad
and update the main history with a negative stat bonus.

STC:
LLR: 2.95 (-2.94,2.94) [0.50,4.50]
Total: 19292 W: 4401 L: 4141 D: 10750
http://tests.stockfishchess.org/tests/view/5d7751d50ebc594e7864973c

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 111952 W: 18762 L: 18275 D: 74915
http://tests.stockfishchess.org/tests/view/5d7771cf0ebc594e786498fa

Closes https://github.com/official-stockfish/Stockfish/pull/2294

Bench: 3914238
 2019-09-11 18:37:08 +02:00
Stefan GeschwentnerandStéphane Nicolet ff69d570d7 Full bonus for LMR stats update 
Simplify previous commit by using the full bonus for LMR-triggered stats update.

STC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 23684 W: 5255 L: 5137 D: 13292
http://tests.stockfishchess.org/tests/view/5d2826660ebc5925cf0d5180

LTC:
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 16245 W: 2832 L: 2704 D: 10709
http://tests.stockfishchess.org/tests/view/5d282e9c0ebc5925cf0d529b

Closes https://github.com/official-stockfish/Stockfish/pull/2236

Bench: 3361902
 2019-07-13 05:49:14 +02:00
Stefan GeschwentnerandStéphane Nicolet 389e60741f Late Move reduction and continuation history 
Update continuation history after LMR-triggered full depth research.
Directly after a LMR-triggered full depth research, we update the
continuation history for quiet moves (but with only half stat bonus).

STC:
LLR: 2.96 (-2.94,2.94) [0.50,4.50]
Total: 39657 W: 8966 L: 8604 D: 22087
http://tests.stockfishchess.org/tests/view/5d279fa40ebc5925cf0d4566

LTC:
LLR: 2.96 (-2.94,2.94) [0.50,3.50]
Total: 32582 W: 5740 L: 5427 D: 21415
http://tests.stockfishchess.org/tests/view/5d27dbf90ebc5925cf0d4b7e

Bench: 3239357
 2019-07-12 09:26:45 +02:00
Stefan GeschwentnerandStéphane Nicolet 368f976fb6 Less LMR at root 
Do no LMR for the first four moves if at root node.

STC:
LLR: 2.95 (-2.94,2.94) [0.50,4.50]
Total: 19686 W: 4524 L: 4261 D: 10901
http://tests.stockfishchess.org/tests/view/5cd3577b0ebc5925cf04a089

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,3.50]
Total: 88335 W: 15193 L: 14766 D: 58376
http://tests.stockfishchess.org/tests/view/5cd35e600ebc5925cf04a1c3

Bench: 3184182
 2019-05-09 15:25:39 +02:00
Stefan GeschwentnerandStéphane Nicolet 28543cddc6 Store only unchanged static evaluations in TT 
A recent commit introduced a decrease of the static evaluation of
an inner node dependent on the previous stat score, which finally
was also stored in the transposition table. Now only the unchanged
static evaluation are stored there.

Remark:
For the case that a static evaluation can be retrieved from the
transposition table the value is now used unchanged. Another test
which also applies the modification in this case failed:
http://tests.stockfishchess.org/tests/view/5b7af6df0ebc5902bdbae2f6

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 6707 W: 1547 L: 1383 D: 3777
http://tests.stockfishchess.org/tests/view/5b7a92df0ebc5902bdbadcf3

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 36203 W: 6046 L: 5781 D: 24376
http://tests.stockfishchess.org/tests/view/5b7abaa10ebc5902bdbadfa9

Closes https://github.com/official-stockfish/Stockfish/pull/1742

Bench: 4457440
 2018-08-20 21:52:29 +02:00
Stefan GeschwentnerandStéphane Nicolet de0889612f Tweak null move pruning conditions 
Allow null move pruning only if last stat score < 30000.

Passed STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 12653 W: 2641 L: 2454 D: 7558
http://tests.stockfishchess.org/tests/view/5af1d8830ebc5968e6523edb

Passed LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 19782 W: 3072 L: 2878 D: 13832
http://tests.stockfishchess.org/tests/view/5af1ee8c0ebc5968e6523ee4

Ideas for further work:

• Tune the stat score threshold.
• Try depth based stat score threshold.
• Try stat score condition for other prunings.

Closes https://github.com/official-stockfish/Stockfish/pull/1589

Bench: 5088156
 2018-05-08 23:31:55 +02:00
Stefan GeschwentnerandMarco Costalba 4bc11984fc Introduce capture history table for capture move sorting 
Introduce capture move history table indexed by moved piece,
target square and captured piece type for sorting capture moves.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 11374 W: 2096 L: 1924 D: 7354
http://tests.stockfishchess.org/tests/view/59fac8dc0ebc590ccbb89fc5

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 24791 W: 3196 L: 3001 D: 18594
http://tests.stockfishchess.org/tests/view/59fae4d20ebc590ccbb89fd9

Bench: 5536775
 2017-11-03 13:57:18 +01:00
Stefan GeschwentnerandJoona Kiiski 69ec09bd4b Bonus for pawn scrifice which create passed pawn 
STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 16752 W: 3141 L: 2944 D: 10667

LTC:
LLR: 3.34 (-2.94,2.94) [0.00,5.00]
Total: 33928 W: 4544 L: 4300 D: 25084

Bench: 5639223

Closes #1092
 2017-05-07 20:51:52 -07:00
Stefan GeschwentnerandMarco Costalba 471f7a1b5c Candidate passed pawns 
Detect safe candidate passers.

STC: http://tests.stockfishchess.org/tests/view/5882395c0ebc5915193f78b3
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 53569 W: 9925 L: 9570 D: 34074

LTC: http://tests.stockfishchess.org/tests/view/5882b4fb0ebc5915193f78e2
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 77576 W: 10387 L: 10014 D: 57175

Bench: 5325829
 2017-01-28 09:04:24 +01:00
Stefan GeschwentnerandMarco Costalba 344616e917 Bonus for attacked passed pawn promotion path 
Bonus for each attacked square on the promotion path
of an enemy passed pawn.

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 141511 W: 25295 L: 24579 D: 91637

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 23161 W: 3022 L: 2831 D: 17308

Bench: 5926706
 2016-10-30 13:48:03 +01:00
Stefan GeschwentnerandMarco Costalba 6aa9308f08 Tweak probcut threshold 
Use better threshold for capture move generation.

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 23265 W: 4415 L: 4188 D: 14662

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,4.00]
Total: 36618 W: 5083 L: 4836 D: 26699

bench: 7030088
 2016-08-29 22:15:03 +02:00
Stefan GeschwentnerandJoona Kiiski a273b6ef8c Add followup moves history for move ordering 
STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 7955 W: 1538 L: 1378 D: 5039

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 5323 W: 778 L: 642 D: 3903

Bench: 8261839

Resolves #599
 2016-03-10 14:26:06 -08:00
Stefan GeschwentnerandJoona Kiiski cccf3c815c Bonus for reachable outpost 
Give a bonus for outpost squares which in reach of a bishop or knight.

STC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 22725 W: 4570 L: 4339 D: 13816

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 15019 W: 2333 L: 2157 D: 10529

Bench: 8503181

Resolves #495
 2015-11-14 06:31:45 -08:00
Stefan GeschwentnerandJoona Kiiski 83e19fbed5 File based passed pawn bonus 
Add file based bonus for passed pawns. Values tuned by SPSA.

STC:
LLR: 3.33 (-2.94,2.94) [0.00,5.00]
Total: 36889 W: 6805 L: 6507 D: 23577

LTC:
LLR: 2.97 (-2.94,2.94) [0.00,5.00]
Total: 32301 W: 5101 L: 4858 D: 22342

Bench: 8073614

Resolves #436
 2015-10-03 03:50:06 -07:00
Stefan GeschwentnerandJoona Kiiski 660c38f781 Scales the endgame score by the number of pawns. 
Credits goes also to Stephane Nicolet for his great idea of scaling by pawns.

STC:
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 9994 W: 1929 L: 1760 D: 6305

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,5.00]
Total: 11240 W: 1789 L: 1626 D: 7825

bench 7298564

Resolves #423
 2015-09-15 05:55:09 -07:00
Stefan GeschwentnerandGary Linscott e14046517e Remove Gain Stats 
Additionally in futility pruning the margin is raised for compensation.

STC
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 48481 W: 9229 L: 9156 D: 30096

LTC
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 32058 W: 5134 L: 5031 D: 21893

Bench: 8098149

Resolves #350
 2015-05-18 13:59:30 -07:00
Stefan GeschwentnerandJoona Kiiski 27efc5ac99 Update stats at pv nodes 
If a quiet best move is found at a pv node then always update stats.

STC:
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 41485 W: 8047 L: 7830 D: 25608

LTC:
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 14351 W: 2420 L: 2250 D: 9681

Bench: 6985247

Resolves #330
 2015-04-10 20:34:55 +01:00
Stefan GeschwentnerandJoona Kiiski ef4d89c9bd update stats also in check 
Update stats also if in check (drop condition).

STC:
LLR: 3.22 (-2.94,2.94) [-3.00,1.00]
Total: 87472 W: 16929 L: 16913 D: 53630

LTC:
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 39971 W: 6436 L: 6345 D: 27190

Bench: 7086031

Resolves #327
 2015-04-09 20:41:08 +01:00
Stefan GeschwentnerandJoona Kiiski 13c11f4048 Introduce Counter Move History tables 
Introduce a counter move history table which additionally is indexed by the last move's piece and target square.
For quiet move ordering use now the sum of standard and counter move history table.

STC:
LLR: 2.96 (-2.94,2.94) [-1.50,4.50]
Total: 4747 W: 1005 L: 885 D: 2857

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 5726 W: 1001 L: 872 D: 3853

Because of reported low NPS on multi core test
STC (7 threads):
ELO: 7.26 +-3.3 (95%) LOS: 100.0%
Total: 14937 W: 2710 L: 2398 D: 9829

Bench: 7725341

Resolves #282
 2015-03-12 07:29:57 +00:00
Stefan GeschwentnerandGary Linscott 18b0809639 Add bonus for pawn attack threats 
Latent pawn attacks: Add a bonus to safe pawn pushes which attacks an
enemy piece.  Based on an idea of Lyudmil Tsvetkov.

STC:
LLR: 2.95 (-2.94,2.94) [-1.50,4.50]
Total: 7925 W: 1666 L: 1537 D: 4722

LTC:
LLR: 2.95 (-2.94,2.94) [0.00,6.00]
Total: 40109 W: 6841 L: 6546 D: 26722

Bench: 7696257

Resolves #240
 2015-02-03 11:19:33 +08:00
Stefan GeschwentnerandJoona Kiiski d8b3ad2208 Fix a skill level problem: Don't allow move pruning at root node 
Bench: 8918745

Resolves #231
 2015-01-25 21:57:13 +00:00
Stefan GeschwentnerandJoona Kiiski 4abe333e1f Enable Futility pruning in PV nodes 
STC:

LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 21553 W: 4342 L: 4221 D: 12990

LTC:

LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 7675 W: 1351 L: 1209 D: 5115

Bench: 8668014

Resolves #205
 2015-01-14 20:13:48 +00:00
Stefan GeschwentnerandGary Linscott 25b492ab58 Big King Safety tuning 
All king safety related terms (shelterweakness, stormdanger,
attackunits, ..) was tuned together. Additionally for attack units a
finer granularity (factor 4) is used.

STC
ELO: 9.22 +-3.1 (95%) LOS: 100.0%
Total: 19514 W: 4340 L: 3822 D: 11352

LTC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 6399 W: 1192 L: 1056 D: 4151

Bench: 8224782

Resolves #184
 2015-01-03 03:33:02 +08:00
Stefan GeschwentnerandGary Linscott 3231038262 Big King Safety tuning 
ShelterWeakness and Stormdanger array are now indexed additionally by
file pair (a/h,b/g,c/f,d/e). The special case of king blocking a pawn
is incorporated in the StormDanger array.  Finally the 93 parameters
are tuned by SPSA on LTC.

STC
ELO: 3.46 +-2.2 (95%) LOS: 99.9%
Total: 40000 W: 8275 L: 7877 D: 23848

LTC
LLR: 2.96 (-2.94,2.94) [0.00,6.00]
Total: 10311 W: 1876 L: 1721 D: 6714

Bench: 9498821

Resolves #163
 2014-12-21 01:53:44 +08:00