Stockfish Testing Queue

Pending - 8 tests 3.4 hrs

30-04-17 Ro InitiativeV2 diff
LLR: -1.34 (-2.94,2.94) [0.00,5.00]
Total: 4594 W: 825 L: 862 D: 2907
sprt @ 10+0.1 th 1 Another pawn asymmetry measure
30-04-17 Ro InitiativeV diff
LLR: -1.69 (-2.94,2.94) [0.00,5.00]
Total: 21000 W: 3809 L: 3791 D: 13400
sprt @ 10+0.1 th 1 Counting rows with black and white pawns
28-04-17 II history diff
LLR: 0.88 (-2.94,2.94) [0.00,4.00]
Total: 63000 W: 11487 L: 11226 D: 40287
sprt @ 10+0.1 th 1 Linear history stats.
19-04-17 vd rsf diff
LLR: -2.21 (-2.94,2.94) [-3.00,1.00]
Total: 63060 W: 7986 L: 8177 D: 46897
sprt @ 60+0.6 th 1 ltc, take 3, param 585
29-04-17 II linear_stats diff
LLR: 0.69 (-2.94,2.94) [0.00,4.00]
Total: 57000 W: 10302 L: 10073 D: 36625
sprt @ 10+0.1 th 1 Take 3 - without excluding low depths.
29-04-17 Vo bestQuietStage diff
LLR: 1.46 (-2.94,2.94) [0.00,5.00]
Total: 61466 W: 11328 L: 11003 D: 39135
sprt @ 10+0.1 th 1 stc
29-04-17 Vo linearStats2 diff
LLR: 1.62 (-2.94,2.94) [0.00,4.00]
Total: 65000 W: 11873 L: 11566 D: 41561
sprt @ 10+0.1 th 1 take 2
28-04-17 Di behind_pawn diff
LLR: -2.68 (-2.94,2.94) [0.00,5.00]
Total: 81000 W: 14612 L: 14383 D: 52005
sprt @ 10+0.1 th 1 Ignore first rank for minor behind pawn

Active - 76 machines 283 cores 1.61M nps (456.68M total nps) 668 games/minute

Machine Cores MNps System Version Running on Last updated
vdv
30
1.41 Linux 4.4.0-72-generic 59 qsTTactualDepth seconds ago
racerschmacer
1
1.56 Windows 10 59 qsTTactualDepth seconds ago
gri
1
2.25 Linux 3.16.0-4-amd64 59 qsTTactualDepth seconds ago
drabel
1
1.41 Windows 10 59 qsTTactualDepth seconds ago
Thanar
3
1.26 Windows 7 59 qsTTactualDepth seconds ago
SFTUser
2
2.04 Windows 10 59 qsTTactualDepth seconds ago
hyperbolic.tom
3
1.31 Linux 4.8.0-41-generic 59 qsTTactualDepth seconds ago
sunu
2
1.51 Linux 4.10.0-0.slh.2-aptosid-amd64 59 qsTTactualDepth 34 minutes ago
SFTUser
2
2.22 Windows 10 59 king_safety seconds ago
Isidor
1
2.60 Windows 8.1 59 king_safety seconds ago
cw
1
1.04 Windows 8.1 59 king_safety seconds ago
amicic
3
2.22 Windows 7 59 king_safety seconds ago
VoyagerOne
5
0.00 Windows 10 59 lmrD 13 minutes ago
crunchy
3
2.25 Windows 7 59 lmrD seconds ago
cw
3
2.25 Windows 8.1 59 lmrD seconds ago
ttruscott
7
1.20 Linux 4.10.8-200.fc25.x86_64 59 lmrD seconds ago
solarlight
3
2.64 Windows 10 59 lmrD seconds ago
chriswk
3
2.50 Linux 4.8.0-22-generic 59 lmrD seconds ago
sqrt2
3
1.99 Linux 3.16.0-4-amd64 59 lmrD seconds ago
Bobo1239
1
1.79 Linux 4.10.9-1-ARCH 59 lmrD seconds ago
joster
3
2.18 Linux 4.4.0-75-generic 59 lmrD seconds ago
SFTUser
2
2.19 Windows 10 59 lmrD seconds ago
witchespics
2
2.25 Windows 10 59 lmrD seconds ago
bigpen0r
15
1.32 Windows 10 59 simplePRO1 seconds ago
velislav
1
2.06 Linux 4.4.0-75-generic 59 simplePRO1 seconds ago
eva42
5
1.22 FreeBSD 11.0-RELEASE-p7 59 simplePRO1 seconds ago
Pking_cda
3
2.24 Linux 4.4.0-59-generic 59 simplePRO1 seconds ago
finfish
3
2.50 Linux 4.4.0-66-generic 59 simplePRO1 seconds ago
drabel
3
2.45 Windows post2008Server 59 simplePRO1 seconds ago
Thanar
3
1.76 Windows 7 59 simplePRO1 seconds ago
achambord
3
1.93 Linux 3.10.23-xxxx-std-ipv6-64 59 simplePRO1 seconds ago
fishtrawler
1
1.34 Linux 3.16.0-042stab120.16 59 simplePRO1 seconds ago
marrco
7
1.42 Windows 8.1 59 simplePRO1 seconds ago
sg4032
5
2.40 Linux 4.4.0-75-generic 59 MinorBehindPawn2 seconds ago
mgrabiak
3
1.43 Windows 8 59 MinorBehindPawn2 seconds ago
SFTUser
2
2.02 Windows 10 59 MinorBehindPawn2 seconds ago
ctoks
3
2.34 Linux 3.4.0+ 59 MinorBehindPawn2 seconds ago
psk
3
2.48 Linux 3.13.0-98-generic 59 MinorBehindPawn2 seconds ago
TueRens
3
2.28 Windows 7 59 MinorBehindPawn2 seconds ago
Pking_cda
3
2.77 Linux 3.13.0-106-lowlatency 59 MinorBehindPawn2 seconds ago
CSU_Dynasty
6
0.71 Windows 7 59 MinorBehindPawn2 seconds ago
IgorLeMasson
2
0.00 Windows 10 59 bound 2 minutes ago
Thanar
3
1.55 Windows 8.1 59 bound seconds ago
SapphireBrand
5
1.97 Windows 7 59 bound seconds ago
cw
3
1.85 Windows 7 59 bound seconds ago
davar
3
1.97 Windows 8.1 59 bound seconds ago
ElbertoOne
3
2.11 Windows 7 59 bound seconds ago
horst.prack
1
1.13 Linux 4.9.0-2-amd64 59 bound seconds ago
AidanWalter
1
1.15 Windows 10 59 bound seconds ago
crunchy
11
1.52 Linux 4.4.0-72-generic 59 excluded seconds ago
crunchy
11
1.50 Linux 4.4.0-72-generic 59 excluded seconds ago
leszek
7
1.02 Windows 7 59 excluded seconds ago
Quaternion
7
2.77 Linux 4.10.11-1-ARCH 59 excluded seconds ago
Prcuvu
7
1.28 Windows 10 59 excluded seconds ago
eva42
4
1.28 Windows 7 59 excluded seconds ago
Fisherman
6
1.66 Windows 8 59 excluded seconds ago
lantonov
1
0.80 Windows 8 59 excluded seconds ago
fastgm
4
1.54 Linux 4.4.0-43-Microsoft 59 excluded seconds ago
cw
5
1.58 Windows 7 59 excluded seconds ago
ctoks
15
1.41 Linux 4.10.0-20-generic 59 excluded seconds ago
aquallung
2
1.06 Windows 7 59 lmrD seconds ago
michael19937
2
1.54 Windows 10 59 lmrD seconds ago
eva42
1
0.91 Linux 3.16.0-4-amd64 59 lmrD seconds ago
cw
1
2.17 Windows 8.1 59 qs_recaptures seconds ago
biffhero
1
1.14 Linux 3.16.0-4-amd64 59 qs_recaptures seconds ago
racerschmacer
1
1.92 Windows 10 59 MinorBehindPawn seconds ago
biffhero
1
1.19 Linux 3.16.0-4-amd64 59 MinorBehindPawn seconds ago
chess_xyz
3
0.94 Windows 7 59 tunePRO1 seconds ago
ali-al-zhrani
2
1.64 Windows 10 59 mate_in_qsearch seconds ago
pb00067
2
2.56 Windows 10 59 mate_in_qsearch seconds ago
horst.prack
1
1.18 Linux 4.9.0-2-amd64 59 mate_in_qsearch seconds ago
velislav
2
1.65 Linux 3.10.0-123.8.1.el7.x86_64 59 mate_in_qsearch 2 minutes ago
jromang
3
1.50 Windows 10 59 mate_in_qsearch seconds ago
Thanar
3
1.26 Windows 10 59 mate_in_qsearch seconds ago
[AMD Users] NeoGen
1
0.96 Windows 7 59 mate_in_qsearch seconds ago
eva42
1
1.52 Linux 3.16.0-4-amd64 59 mate_in_qsearch 2 minutes ago
30-04-17 ma excluded diff
LLR: 0.87 (-2.94,2.94) [-3.00,1.00]
Total: 4907 W: 621 L: 584 D: 3702
sprt @ 60+0.6 th 1 LTC [Simplification]: Removing excluded move from posKey formula. This is safe to do, because positions with excluded move are not saved to the TT table.
30-04-17 vd lmrD diff
LLR: 0.01 (-2.94,2.94) [0.00,5.00]
Total: 1916 W: 330 L: 322 D: 1264
sprt @ 10+0.1 th 1 stc, take 3, param 0, 3000.
30-04-17 fa simplePRO1 diff
LLR: -0.21 (-2.94,2.94) [-3.00,1.00]
Total: 3352 W: 604 L: 621 D: 2127
sprt @ 10+0.1 th 1 A simple version of King Protector, with tuned values
30-04-17 Vo qsTTactualDepth diff
LLR: -1.19 (-2.94,2.94) [0.00,5.00]
Total: 10834 W: 1983 L: 1987 D: 6864
sprt @ 10+0.1 th 1 Use actual depth for TT in QS
30-04-17 Ha bound diff
LLR: -0.95 (-2.94,2.94) [0.00,4.00]
Total: 7687 W: 1361 L: 1385 D: 4941
sprt @ 10+0.1 th 1 Bugfix: Ensure correct qs score bounds
27-04-17 fa tunePRO1 diff
55582/60000 iterations
113701/120000 games played
120000 @ 10+0.1 th 1 Still in phase one, but increasing the ck to speedup the process
30-04-17 sg MinorBehindPawn2 diff
LLR: 0.92 (-2.94,2.94) [0.00,5.00]
Total: 8173 W: 1517 L: 1443 D: 5213
sprt @ 10+0.1 th 1 No MinorBehindPawn bonus if piece is behind an opponent passed pawn. This removes overlap with passed pawn evaluation. No compensation.
30-04-17 II king_safety diff
LLR: 1.56 (-2.94,2.94) [0.00,4.00]
Total: 11507 W: 2140 L: 2018 D: 7349
sprt @ 10+0.1 th 1 Combo with rook mobility bonus.
28-04-17 pb mate_in_qsearch diff
LLR: -0.76 (-2.94,2.94) [-3.00,1.00]
Total: 86888 W: 11019 L: 11168 D: 64701
sprt @ 60+0.6 th 1 LTC: Simplification for mate detection in qsearch (bench changes at higher depths)
30-04-17 sg MinorBehindPawn diff
LLR: -1.88 (-2.94,2.94) [0.00,5.00]
Total: 31472 W: 5694 L: 5640 D: 20138
sprt @ 10+0.1 th 1 No MinorBehindPawn bonus if piece is behind an own passed pawn
30-04-17 vd lmrD diff
LLR: 0.07 (-2.94,2.94) [0.00,5.00]
Total: 16866 W: 3092 L: 3017 D: 10757
sprt @ 10+0.1 th 1 stc, take 2, param 1000 3000
30-04-17 sn qs_recaptures diff
LLR: -2.17 (-2.94,2.94) [0.00,4.00]
Total: 34193 W: 6201 L: 6199 D: 21793
sprt @ 10+0.1 th 1 Change posKey in recapture stage. See discussion in https://github.com/official-stockfish/Stockfish/pull/1088

Finished - 17428 tests

30-04-17 SC blockedKing diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 3782 W: 600 L: 709 D: 2473
sprt @ 10+0.1 th 1 Take 3.
30-04-17 sg MinorBehindPawn2 diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 19906 W: 3606 L: 3646 D: 12654
sprt @ 10+0.1 th 1 No MinorBehindPawn bonus if piece is behind an own pawn which is not defended by a pawn
30-04-17 II king_safety diff
LLR: -2.96 (-2.94,2.94) [0.00,4.00]
Total: 29142 W: 5189 L: 5247 D: 18706
sprt @ 10+0.1 th 1 King safety parameters 'by feeling' - based on several tunings.
30-04-17 ma excluded diff
LLR: 2.95 (-2.94,2.94) [-3.00,1.00]
Total: 27206 W: 4923 L: 4813 D: 17470
sprt @ 10+0.1 th 1 STC [Simplification]: Removing excluded move from posKey formula. This is safe to do, because positions with excluded move are not saved to the TT table.
30-04-17 Vo DepthNone diff
LLR: -0.45 (-2.94,2.94) [-3.00,1.00]
Total: 3424 W: 571 L: 600 D: 2253
sprt @ 10+0.1 th 1 Bug Fix: DepthNone = -6. However we can reach much lower depth...I think the lowest possible is -13.
30-04-17 vd lmrD diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 13710 W: 2444 L: 2511 D: 8755
sprt @ 10+0.1 th 1 stc (corrected logic), param 8000, 3000
30-04-17 SC blockedKing diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 26196 W: 4643 L: 4658 D: 16895
sprt @ 10+0.1 th 1 Take 2.
30-04-17 sg MinorBehindPawn diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 11951 W: 2166 L: 2240 D: 7545
sprt @ 10+0.1 th 1 No MinorBehindPawn bonus if piece is attacked by a pawn
29-04-17 fa simplePRO diff
LLR: -2.95 (-2.94,2.94) [-3.00,1.00]
Total: 45059 W: 8171 L: 8406 D: 28482
sprt @ 10+0.1 th 1 A halfway check for the simpler version of King protector
30-04-17 ma excluded diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 30200 W: 5401 L: 5398 D: 19401
sprt @ 10+0.1 th 1 Removing excluded move from posKey formula. This is save to do, because positions with excluded move are not saved to the TT table.
29-04-17 SC blockedKing diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 34609 W: 6296 L: 6273 D: 22040
sprt @ 10+0.1 th 1 Bugfix
28-04-17 sn removeOldAlpha diff
ELO: 2.58 +-4.4 (95%) LOS: 87.5%
Total: 7000 W: 1045 L: 993 D: 4962
7000 @ 5+0.05 th 11 Verification test for PR #1088
29-04-17 Vo bestQuietStage2 diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 16147 W: 2914 L: 2970 D: 10263
sprt @ 10+0.1 th 1 ver 2
29-04-17 SC kingDanger diff
LLR: -2.96 (-2.94,2.94) [0.00,4.00]
Total: 17856 W: 3230 L: 3326 D: 11300
sprt @ 10+0.1 th 1 And btw, why we throw out information we painfully acquired?
29-04-17 Vo mateTT diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 21675 W: 3917 L: 3950 D: 13808
sprt @ 10+0.1 th 1 Save mates in TT
28-04-17 sg passed_pawn_break2 diff
LLR: 3.34 (-2.94,2.94) [0.00,5.00]
Total: 33928 W: 4544 L: 4300 D: 25084
sprt @ 60+0.6 th 1 LTC: Version of my last try with half eval (+ fix of assert in evaluate_passed_pawns). Set prio to -1 to wait for the other version.
29-04-17 jh king_danger_1 diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 9450 W: 1737 L: 1822 D: 5891
sprt @ 10+0.1 th 1 Adjust king danger with presence of Rook.
29-04-17 SC blockedKing diff
LLR: 0.40 (-2.94,2.94) [0.00,5.00]
Total: 1262 W: 235 L: 213 D: 814
sprt @ 10+0.1 th 1 If king is safe, leave a bit of space in the king ring, just in case. Take 1.
29-04-17 sg passed_pawn_break3 diff
LLR: -0.02 (-2.94,2.94) [0.00,5.00]
Total: 18653 W: 3367 L: 3289 D: 11997
sprt @ 10+0.1 th 1 Try only quarter bonus
28-04-17 Vo linearStats diff
LLR: -2.95 (-2.94,2.94) [0.00,4.00]
Total: 31826 W: 4033 L: 4098 D: 23695
sprt @ 60+0.6 th 1 LTC: My try on linear stats
29-04-17 sn passed_pawns4 diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 29022 W: 5182 L: 5185 D: 18655
sprt @ 10+0.1 th 1 Score connected passed pawns in pawns.cpp, take 2
29-04-17 sn qs_pruning' diff
LLR: -2.95 (-2.94,2.94) [-3.00,1.00]
Total: 11543 W: 1999 L: 2175 D: 7369
sprt @ 10+0.1 th 1 Suppress second case of futility pruning in qsearch()
29-04-17 sn qs_pruning diff
LLR: -2.96 (-2.94,2.94) [-3.00,1.00]
Total: 3834 W: 639 L: 804 D: 2391
sprt @ 10+0.1 th 1 No futility pruning in quiescence search
28-04-17 nh trapped_rook diff
LLR: -2.95 (-2.94,2.94) [0.00,4.00]
Total: 50269 W: 9023 L: 9009 D: 32237
sprt @ 10+0.1 th 1 Trapped rook separated no castle case + parameter tweak
28-04-17 Sa LMRRetreatRefinement diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 29225 W: 5157 L: 5159 D: 18909
sprt @ 10+0.1 th 1 Another shot at LMR for retreats.
28-04-17 Fi endSwap diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 21328 W: 3815 L: 3850 D: 13663
sprt @ 10+0.1 th 1 Take 2
28-04-17 Vo linearStats diff
LLR: 2.96 (-2.94,2.94) [0.00,4.00]
Total: 17056 W: 3119 L: 2906 D: 11031
sprt @ 10+0.1 th 1 My try on linear stats
27-04-17 sg passed_pawn_break diff
LLR: -1.08 (-2.94,2.94) [0.00,5.00]
Total: 69516 W: 9014 L: 8833 D: 51669
sprt @ 60+0.6 th 1 LTC: Bonus for pawn sacrifice which creates an advanced passed pawn
28-04-17 Vo qsPlayedMove diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 16007 W: 2891 L: 2948 D: 10168
sprt @ 10+0.1 th 1 Never update TT in QS if no moves are played...
28-04-17 sg passed_pawn_break2 diff
LLR: -1.08 (-2.94,2.94) [0.00,5.00]
Total: 30872 W: 5648 L: 5562 D: 19662
sprt @ 10+0.1 th 1 LTC struggles, so try some variations of this idea.
28-04-17 sg passed_pawn_break2 diff
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 16752 W: 3141 L: 2944 D: 10667
sprt @ 10+0.1 th 1 Version of my last try with half eval (+ fix of assert in evaluate_passed_pawns). Set prio to -1 to wait for the other version.
28-04-17 pb mate_in_qsearch diff
LLR: 2.96 (-2.94,2.94) [-3.00,1.00]
Total: 19067 W: 3451 L: 3327 D: 12289
sprt @ 10+0.1 th 1 Simplification for mate detection in qsearch (bench changes at higher depths)
28-04-17 sn passed_pawns3 diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 30574 W: 5491 L: 5487 D: 19596
sprt @ 10+0.1 th 1 Take 2
28-04-17 pb lmr_full diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 15297 W: 2696 L: 2757 D: 9844
sprt @ 10+0.1 th 1 Don't research on LMR high-fail when searched just one ply behind
28-04-17 II history diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 5638 W: 948 L: 1049 D: 3641
sprt @ 10+0.1 th 1 Don't update history stats at low depths.
27-04-17 vd threading2 diff
ELO: -3.39 +-5.8 (95%) LOS: 12.7%
Total: 4000 W: 566 L: 605 D: 2829
4000 @ 5+0.05 th 11 elo estimate v5
27-04-17 vd threading2 diff
ELO: -92.92 +-6.4 (95%) LOS: 0.0%
Total: 4000 W: 222 L: 1267 D: 2511
4000 @ 5+0.05 th 11 elo estimate v6
27-04-17 Sa MovePickStageConditionI diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 29642 W: 5283 L: 5283 D: 19076
sprt @ 10+0.1 th 1 Testing a hunch for LMR.
27-04-17 sn iid3 diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 27317 W: 4859 L: 4869 D: 17589
sprt @ 10+0.1 th 1 Remove an epsilon of room for internal iterative deepening
27-04-17 Gu crossed diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 10330 W: 1778 L: 1860 D: 6692
sprt @ 10+0.1 th 1 Crossed pawns
27-04-17 Fi endSwap diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 25568 W: 4622 L: 4638 D: 16308
sprt @ 10+0.1 th 1 Optimize partial sort by swapping worse items to the end.
27-04-17 pb root_move_lmr diff
LLR: -2.98 (-2.94,2.94) [0.00,5.00]
Total: 50163 W: 6482 L: 6439 D: 37242
sprt @ 60+0.6 th 1 LTC As queue rather empty, testing a weird root-move-lmr idea.
27-04-17 Vo qsPruning2 diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 28634 W: 5197 L: 5200 D: 18237
sprt @ 10+0.1 th 1 Based off and against recent passed patch
27-04-17 sn passed_pawns3 diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 23087 W: 4107 L: 4135 D: 14845
sprt @ 10+0.1 th 1 Tell apart passed pawns and candidate passed pawns.
27-04-17 fa tunePRO diff
9311/75000 iterations
19096/150000 games played
150000 @ 10+0.1 th 1 Tuning a new simpler version of King Protector in cooperation with Rocky (First step)
27-04-17 Ro BackwardRank4 diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 9991 W: 1757 L: 1840 D: 6394
sprt @ 10+0.1 th 1 Do not consider a pawn backward when on rank_4 and weakly controlled.
27-04-17 Ro BackwardRank4 diff
LLR: -2.97 (-2.94,2.94) [0.00,5.00]
Total: 7924 W: 1361 L: 1453 D: 5110
sprt @ 10+0.1 th 1 Take 2
27-04-17 Gu blocked diff
LLR: -2.95 (-2.94,2.94) [0.00,5.00]
Total: 2862 W: 492 L: 606 D: 1764
sprt @ 10+0.1 th 1 If opposed pawn = blocked pawn
27-04-17 sn iid3 diff
LLR: -2.96 (-2.94,2.94) [0.00,5.00]
Total: 9810 W: 1698 L: 1782 D: 6330
sprt @ 10+0.1 th 1 Give an epsilon of room to internal iterative deepening
27-04-17 sg passed_pawn_break diff
LLR: 2.95 (-2.94,2.94) [0.00,5.00]
Total: 5934 W: 1160 L: 1009 D: 3765
sprt @ 10+0.1 th 1 Bonus for pawn sacrifice which creates an advanced passed pawn