Test position

[Daniel White]

Hello Daniel:

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

What say your engine?

Is anyone able to explain how white proceeds after 1. Qf6+ Bxf6 2. gxf6+ Kg8 ?

Of course: Houdini thinks that this variation ends with a mate in eight:

Rxh7, Kxh7; Rh3+, Kg8; Ah6, Qc7; f4 (defending e5), Qa5; Bg7, Qa1+; Kf2, Qf1+; Kxf1, Rfe8; Rh8#.

If Qf6+, Kg8 then the same idea applies if we trust Spark and its line of mate in ine after Kg8:

Rxh7, Bxf6 (not Kxh7?; Rh3+, Kg8 (only move); Rh8#); gxf6, Kxh7; Rh3+, Kg8; Ah6, Qc7; f4 (defending e5), Qa5; Bg7, Qa1+; Kf2, Qe1+; Kxe1, Rfb8; Rh8#.

If you take a look, you will see that all the plans for white are the same after Qf6+: rook sacrifice on h7 square, rook check in h3, Qc7 for black aiming for Qe5+ with advantage for black (avoiding the checkmate plan by white), f4 for defending white pawn on e5, then some checks by the black queen while white plays Bh6, Bg7, Rh8# due to the black king is trapped by its own pieces.

I hope that my explanation is clear enough. Please ask again if you have more doubts: someone will kindly answer you.

Regards from Spain.

Ajedrecista.

Thanks for the quick response, it makes perfect sense now.

[zullil]

Hello Tony:

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

What say your engine?

Qf6+ was tempting for this position, even for me. OTOH, Spark is Spark...

Just for fun, here's Spark-1.0 with 8 threads and 2GB hash. Qf6+ in less than a second:

Code: Select all

id name spark-1.0
id author AJ Siemelink
option name UCI_EngineAbout type string default spark-1.0 by AJ Siemelink
option name UCI_Opponent    type string
option name UCI_AnalyseMode type check default false
option name Threads         type spin   default 16 min 1 max 16
option name Hash            type spin   default 32 min 1 max 4096
option name Ponder          type check  default true
option name MultiPV         type spin   default 1 min 1 max 256
option name MultiPVMargin   type spin   default 100 min 0 max 2000
option name OwnBook         type check  default true
option name eval.mobility.opening      type spin default 100 min 0 max 1000
option name eval.mobility.endgame      type spin default 100 min 0 max 1000
option name eval.passedpawns.opening   type spin default 100 min 0 max 1000
option name eval.passedpawns.endgame   type spin default 100 min 0 max 1000
option name eval.pawnstructure.opening type spin default 100 min 0 max 1000
option name eval.pawnstructure.endgame type spin default 100 min 0 max 1000
option name eval.kingattack            type spin default 100 min 0 max 1000
uciok
setoption name Threads value 8
setoption name Hash value 2048
position fen r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19
isready
readyok
go infinite
info depth 1 currmovenumber 1 currmove h2h3 time 0 nodes 0 hashfull 0
info depth 1 seldepth 0 score cp -53 time 1 nodes 1 hashfull 0 pv h2h3
info depth 1 seldepth 0 score cp -50 time 1 nodes 10 hashfull 0 pv c3e2
info depth 1 seldepth 0 score cp -39 time 1 nodes 13 hashfull 0 pv e3c1
info depth 1 seldepth 0 score cp -33 time 1 nodes 15 hashfull 0 pv e3d2
info depth 1 seldepth 0 score cp -9 time 1 nodes 36 hashfull 0 pv g3h3
info depth 1 seldepth 0 score cp -1 time 1 nodes 45 hashfull 0 pv e1f1
info depth 2 currmovenumber 1 currmove e1f1 time 1 nodes 85 hashfull 0
info depth 2 seldepth 1 score cp -5 time 1 nodes 129 hashfull 0 pv e1f1 b7c6
info depth 2 seldepth 1 score cp 2 time 2 nodes 1371 hashfull 0 pv g3h3 f8h8
info depth 3 currmovenumber 1 currmove g3h3 time 2 nodes 1495 hashfull 0
info depth 3 seldepth 2 score cp -24 time 2 nodes 1740 hashfull 0 pv g3h3 f8h8 h4f4
info depth 3 seldepth 2 score cp 11 time 2 nodes 2401 hashfull 0 pv e1f1 b7c6 g3h3
info depth 4 currmovenumber 1 currmove e1f1 time 3 nodes 2706 hashfull 0
info depth 4 seldepth 4 score cp 7 time 3 nodes 4211 hashfull 0 pv e1f1 f8h8 f1g1 b7c6
info depth 5 currmovenumber 1 currmove e1f1 time 4 nodes 4926 hashfull 0
info depth 5 seldepth 6 score cp 5 time 4 nodes 5281 hashfull 0 pv e1f1 f8h8 f1g1 b7c6 e3d2
info depth 6 currmovenumber 1 currmove e1f1 time 5 nodes 10002 hashfull 0
info depth 6 seldepth 9 score cp 5 time 5 nodes 11174 hashfull 0 pv e1f1 f8h8 f1g1 b7c6 e3d2 d8c7
info depth 7 currmovenumber 1 currmove e1f1 time 7 nodes 16633 hashfull 0
info depth 7 seldepth 11 score cp 2 time 8 nodes 24511 hashfull 0 pv e1f1 f8h8 h4f4 d8e8 e3d2 b7c6 f1g1
info depth 8 currmovenumber 1 currmove e1f1 time 13 nodes 51866 hashfull 0
info depth 8 seldepth 14 score cp -23 upperbound time 16 nodes 74191 hashfull 0 pv e1f1 f8h8 h4f4 d8e8 e3d2 b7c6 f1g1
info depth 8 currmovenumber 1 currmove e1f1 time 43 nodes 257935 hashfull 0
info depth 8 seldepth 20 score cp -20 time 43 nodes 260144 hashfull 0 pv e1f1 f8h8 e3c1 b7c6 c1d2 d8c7 h4f4 a8f8
info depth 9 currmovenumber 1 currmove e1f1 time 43 nodes 260189 hashfull 0
info depth 9 seldepth 20 score cp -17 time 52 nodes 333301 hashfull 0 pv e1f1 f8h8 h4f4 d8e8 c3a4 e8b5 c2c4 d5c4 f4f7 g7g8 f3f4 c4b3 f1g1
info depth 10 currmovenumber 1 currmove e1f1 time 76 nodes 521451 hashfull 1
info depth 10 seldepth 20 score cp -28 time 95 nodes 705135 hashfull 1 pv e1f1 d8c7 e3f4 g7g8 g3h3 h7h5 f1g1 d5d4 c3e4 b7c6
info depth 11 currmovenumber 1 currmove e1f1 time 161 nodes 1323470 nps 8220310 hashfull 3
info depth 11 seldepth 22 score cp -50 time 172 nodes 1446176 nps 8408000 hashfull 3 pv e1f1 d8c7 e3f4 f8h8 g3h3 d5d4 c3e4 c7a5 f4c1 c5c4 f1g2 a5e5 b3c4
info depth 11 seldepth 24 score cp -46 time 280 nodes 2589574 nps 9248478 hashfull 5 pv f3f4 f8h8 g3f3 d8e8 e3d2 d5d4 c3e4 b7e4 f4e4 e8b5 e4f4
info depth 11 currmovenumber 12 currmove g3g1 time 280 nodes 2589574 nps 9248478 hashfull 5
info depth 11 currmovenumber 35 currmove e1d2 time 382 nodes 3726829 nps 9756096 hashfull 8
info depth 12 currmovenumber 1 currmove f3f4 time 409 nodes 3994158 nps 9765667 hashfull 9
info depth 12 seldepth 24 score cp -21 lowerbound time 416 nodes 4050752 nps 9737384 hashfull 9 pv f3f4 f8h8
info depth 12 currmovenumber 1 currmove f3f4 time 416 nodes 4050752 nps 9737384 hashfull 9
info depth 12 seldepth 24 score cp -28 time 437 nodes 4281034 nps 9796416 hashfull 9 pv f3f4 f8h8 g3f3 d8e8 e3d2 d5d4 c3e4 b7e4 f4e4 e8b5 e4f4 h8f8 c2c4 d4c3 f3c3
info depth 12 currmovenumber 7 currmove c3b1 time 573 nodes 6049652 nps 10557856 hashfull 13
info depth 12 currmovenumber 25 currmove f3g4 time 680 nodes 7364222 nps 10829738 hashfull 16
info depth 13 currmovenumber 1 currmove f3f4 time 749 nodes 8098558 nps 10812493 hashfull 18
info depth 13 seldepth 28 score cp -17 time 784 nodes 8517936 nps 10864714 hashfull 18 pv f3f4 f8h8 g3f3 d8e8 e3d2 a8b8 e1f1 b7c6 f3h3 c5c4 b3c4 d5c4 d2c1
info depth 13 currmovenumber 8 currmove c3b5 time 855 nodes 9455694 nps 11059291 hashfull 20
info depth 13 currmovenumber 21 currmove h2h3 time 958 nodes 10716695 nps 11186529 hashfull 23

info depth 13 seldepth 31 score cp -3 lowerbound time 991 nodes 11009287 nps 11109270 hashfull 23 pv f3f6 e7f6
info depth 13 currmovenumber 1 currmove f3f6 time 991 nodes 11009287 nps 11109270 hashfull 23
info depth 13 seldepth 31 score cp 22 lowerbound time 1002 nodes 11140917 nps 11118679 hashfull 23 pv f3f6 e7f6
info depth 13 currmovenumber 1 currmove f3f6 time 1002 nodes 11140917 nps 11118679 hashfull 23
info depth 13 seldepth 31 score cp 122 lowerbound time 1008 nodes 11187846 nps 11099053 hashfull 24 pv f3f6 e7f6
info depth 13 currmovenumber 1 currmove f3f6 time 1008 nodes 11187846 nps 11099053 hashfull 24
info depth 13 seldepth 31 score cp 372 lowerbound time 1048 nodes 11734986 nps 11197505 hashfull 25 pv f3f6 e7f6
info depth 13 currmovenumber 1 currmove f3f6 time 1048 nodes 11734986 nps 11197505 hashfull 25
info depth 13 seldepth 31 score cp 469 time 1389 nodes 17039192 nps 12267236 hashfull 36 pv f3f6 e7f6 g5f6 d8f6 e5f6 g7f6 e3c5 f8e8 h4h7 d5d4 c5d4 e6e5 d4e3 e8h8 e3g5 f6e6 g3h3 h8h7 h3h7 b7f3
info depth 13 currmovenumber 3 currmove e1f1 time 1389 nodes 17039192 nps 12267236 hashfull 36
info depth 14 currmovenumber 1 currmove f3f6 time 1397 nodes 17132801 nps 12263994 hashfull 36
info depth 14 seldepth 32 score cp 463 time 1560 nodes 19846066 nps 12721837 hashfull 41 pv f3f6 e7f6 g5f6 d8f6 e5f6 g7f6 e3c5 f8e8 h4h7 d5d4 c5d4 e6e5 d4e3 e8h8 e3g5 f6e6 g3h3 h8h7 h3h7 b7f3 h7h3

[zullil]

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

What say your engine?

This position is interesting, in the sense that it's a rare tactical middlegame position that seems to be solved more easily by humans than by engines. Like others did, I took one glance at the position and the "plan" was obvious: The black king must be forced back to prevent the rook on f8 from reinforcing on h8. And the pawn on g5 needs to move, to clear an entry path for the bishop on e3. Thus Qf6+.

Got this one 4 minutes ahead of Critter-1.6a (8 threads, 4GB hash). Now that's unusual.

[Vinvin]

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

CPU0: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU1: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU2: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU3: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU4: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU5: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
6 processor(s) found, POPCNT available

Houdini

24/59 2:22 -0.23++ 1.Qf6+ (2.321.253.218) 16314
24/59 2:27 -0.10++ 1.Qf6+ (2.398.398.613) 16293
24/59 2:44 +0.17++ 1.Qf6+ (2.672.284.807) 16276
24/64 4:24 +1.08++ 1.Qf6+ (4.322.509.830) 16353
24/64 4:27 +1.08 1.Qf6+ Bxf6 2.gxf6+ Kg8 3.Bxc5 Re8 (4.372.821.339) 16366

Rybka

19.20 0:40 -0.28++ 1.Qf6+ Bxf6 2.gxf6+ (27.828.681) 682
19.01 0:40 -0.13++ 1.Qf6+ Bxf6 2.gxf6+ (27.898.661) 681
19.01 0:44 +0.27++ 1.Qf6+ Bxf6 2.gxf6+ (29.182.709) 662
19.01 1:00 +1.07++ 1.Qf6+ Bxf6 2.gxf6+ (36.083.877) 593
19.01 1:14 +1.07++ 1.Qf6+ Bxf6 2.gxf6+ (41.666.560) 563

Houdini is particularly slow on this one.

[Terry McCracken]

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

CPU0: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU1: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU2: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU3: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU4: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
CPU5: GenuineIntel Intel64 Family 6 Model 44 Stepping 2 3373 MHz
6 processor(s) found, POPCNT available

Houdini

24/59 2:22 -0.23++ 1.Qf6+ (2.321.253.218) 16314
24/59 2:27 -0.10++ 1.Qf6+ (2.398.398.613) 16293
24/59 2:44 +0.17++ 1.Qf6+ (2.672.284.807) 16276
24/64 4:24 +1.08++ 1.Qf6+ (4.322.509.830) 16353
24/64 4:27 +1.08 1.Qf6+ Bxf6 2.gxf6+ Kg8 3.Bxc5 Re8 (4.372.821.339) 16366

Rybka

19.20 0:40 -0.28++ 1.Qf6+ Bxf6 2.gxf6+ (27.828.681) 682
19.01 0:40 -0.13++ 1.Qf6+ Bxf6 2.gxf6+ (27.898.661) 681
19.01 0:44 +0.27++ 1.Qf6+ Bxf6 2.gxf6+ (29.182.709) 662
19.01 1:00 +1.07++ 1.Qf6+ Bxf6 2.gxf6+ (36.083.877) 593
19.01 1:14 +1.07++ 1.Qf6+ Bxf6 2.gxf6+ (41.666.560) 563

Houdini is particularly slow on this one.

It really is. I'd like to see a few more engines working on this one.

[Terry McCracken]

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

What say your engine?

Tony, what game is this position taken from?

[jdart]

This is from Asauskas-Malisauskas, Vilnius 2004 - it was in a test suite from W. Eigenmann (Nightmare Nr. 019).

--Jon

[tttony]

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

What say your engine?

Tony, what game is this position taken from?

You can see here: http://www.chessgames.com/perl/chessgame?gid=1673496

[Terry McCracken]

[d] r2q1r2/1b2bpkp/p3p1p1/2ppP1P1/7R/1PN1BQR1/1PP2P1P/4K3 w - - 4 19

What say your engine?

Tony, what game is this position taken from?

You can see here: http://www.chessgames.com/perl/chessgame?gid=1673496

Thanks Guys!

[lech]

Sting 1,0 can do it in a few seconds on a very fast computer.
It is a pity that I gave up this wonderful idea (the ELO pressure).