Which engines allow Black knight sac for three pawns here?

[Graham Banks]

[d]r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R W

Two very strong engines have recently played Bd3 here, allowing black to play Nxf4.
After Bxf4, dxc4; Ne2, dxe5; the resulting big pawn phalanx has then given black a big advantage.

[tpetzke]

Hi Graham,

is this the right position. I don't see how an engine (especially a strong one) can play Bd3 here. It will lose due to sending an illegal move.

Thomas...

[Codesquid]

Assuming you mean Be3, Octochess occasionally wants to play it, though exd or dxc eventually replace it if searching deep enough:

Code: Select all

 20	0.00	350.0M	0:41.27	d4xc5    d6xe5    f4xe5   Nd7xe5   Qd1-e2   Ne5xf3   Qe2xf3      O-O      O-O   Qd8-a5    g2-g4   Bg7xc3    b2xc3   Nh5-f6   Bc1-h6   Rf8-d8    g4-g5   Qa5xc5   Kg1-h1   Nf6-h5   
 19	+0.18	248.7M	0:30.43	d4xc5    d6xe5    f4xe5   Nd7xe5   Qd1-e2   Ne5xf3   Qe2xf3      O-O      O-O   Qd8-a5    g2-g4   Bg7xc3    b2xc3   Nh5-f6   Bc1-h6   Rf8-d8    g4-g5   Qa5xc5   Kg1-h1   
 19	-0.04	167.9M	0:21.44	e5xd6      O-O      O-O    e7xd6   Bc1-e3   Rf8-e8   Qd1-d2   Nd7-b6    b2-b3    f7-f5   Ra1-e1    c5-c4   Kg1-h1    c4xb3    c2xb3   Ra8-c8    a2-a4   Qd8-d7   Nc3-b5   
 19	-0.16	137.5M	0:18.20	Bc1-e3   Nh5xf4   Be3xf4    c5xd4   Nc3-e2    d6xe5   Bf4-g3   Qd8-b6    c2-c3   Ra8-d8    c3xd4    e5xd4   Bg3-f2   Nd7-c5      O-O    e7-e5   Ra1-c1      O-O   Kg1-h1   
 18	+0.14	75.8M	0:11.32	Bc1-e3   Nh5xf4   Be3xf4    c5xd4   Nc3-e2    d6xe5   Bf4-g3    f7-f5   Qd1-d2    f5-f4   Bg3-h4    h7-h6    O-O-O    g6-g5   Bh4-f2      O-O   Qd2-d3   Qd8-b6   
 17	+0.06	34.6M	0:06.38	Bc1-e3   Nh5xf4   Be3xf4    c5xd4   Nc3-e2    d6xe5   Bf4-g3    f7-f5   Qd1-d2   Ra8-c8    O-O-O      O-O   Qd2-b4    f5-f4   Bg3-h4   Nd7-c5   Qb4-c4   
 16	+0.02	19.1M	0:04.40	Bc1-e3   Nh5xf4   Be3xf4    c5xd4   Nc3-e2    d6xe5   Bf4-g3    f7-f5   Qd1-d2   Ra8-c8    O-O-O      O-O   Kc1-b1    f5-f4   Bg3-h4   Nd7-c5   
 15	+0.20	11.8M	0:03.41	Bc1-e3   Nh5xf4   Be3xf4    c5xd4   Nc3-e2    d6xe5   Bf4-g3   Qd8-a5    c2-c3    d4xc3    b2xc3    O-O-O      O-O   Nd7-c5   Qd1-c2   
 14	+0.29	8.7M	0:02.87	Bc1-e3   Nh5xf4   Be3xf4    c5xd4   Nc3-e2    d6xe5   Bf4-g3   Qd8-a5    c2-c3    d4xc3    b2xc3    O-O-O      O-O   Nd7-c5   
 14	-0.03	6.6M	0:02.42	e5xd6      O-O      O-O    e7xd6   Bc1-e3   Rf8-e8   Qd1-d2   Nd7-b6   Qd2-d3    c5-c4   Qd3-d2   Nh5-f6    d4-d5   Nf6-g4   
 13	+0.12	3.8M	0:01.73	e5xd6      O-O      O-O    e7xd6   Rf1-e1   Nd7-b6    g2-g4   Bg7xd4   Nf3xd4    c5xd4   Nc3-b5   Nh5-f6   Nb5xd4   
 12	+0.14	2.7M	0:01.40	e5xd6      O-O      O-O    e7xd6   Rf1-e1   Rf8-e8   Re1xe8   Qd8xe8   Nc3-b5   Qe8-e7    d4xc5    d6xc5   
 11	+0.14	1.8M	0:01.01	e5xd6      O-O      O-O    e7xd6   Rf1-e1    f7-f5   Bc1-e3   Qd8-b6    b2-b3   Rf8-e8   Nc3-d5   

[Graham Banks]

Hi Graham,

is this the right position. I don't see how an engine (especially a strong one) can play Bd3 here. It will lose due to sending an illegal move.

Thomas...

Yes - I meant Be3.

[velmarin]

There e6.
Analysis by Bouquet 1.8b x64:
1. = (0.00): 1.Ae3 Cxf4 2.Axf4 cxd4 3.e6 fxe6 4.Cxd4 Axd4 5.Dxd4 e5 6.Axe5 Cxe5 7.0-0-0 Da5 8.Cd5 Dxa2 9.Cc7+ Rf7 10.Cxa8 Txa8 11.Thf1+ Rg7 12.Tf3 Da1+ 13.Rd2 Da5+ 14.Rc1 Da1+
2. = (-0.11): 1.dxc5 dxe5 2.fxe5 Cxe5 3.De2 Cxf3+ 4.Dxf3 Da5 5.Ad2 Dxc5 6.0-0-0 Dc6 7.Dxc6+ bxc6 8.The1 Td8 9.Te4 Td4 10.Ae3 Txd1+ 11.Cxd1 f5 12.Ta4 Rf7 13.Txa7 Td8

[D]r2qk2r/pp1nppbp/3pP1p1/8/3p1B2/2N2N2/PPP3PP/R2QK2R b KQkq - 0 3

[zullil]

[d]r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R W

The position field might be OK, but the FEN above is invalid. (When I copied it into Stockfish, the engine analyzed the position as if Black were to move!)

This seems better: r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R w KQkq -

Stockfish goes for exd6:

Code: Select all

info depth 30 seldepth 42 score cp 0 nodes 907095890 nps 7552146 time 120111 multipv 1 pv e5d6 e8g8 e1g1 e7d6 a2a4 h5f6 f4f5 d8b6 a4a5 b6c6 f5g6 f7g6 f1e1 a8e8 d4d5 c6a6 e1e6 f6g4 c3e4 d7f6 e4c3 f6h5 c3e4 h5f6

[Vinvin]

2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R W

The position field might be OK, but the FEN above is invalid. (When I copied it into Stockfish, the engine analyzed the position as if Black were to move!)

This seems better: r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R w KQkq -

Stockfish goes for exd6:

Code: Select all

info depth 30 seldepth 42 score cp 0 nodes 907095890 nps 7552146 time 120111 multipv 1 pv e5d6 e8g8 e1g1 e7d6 a2a4 h5f6 f4f5 d8b6 a4a5 b6c6 f5g6 f7g6 f1e1 a8e8 d4d5 c6a6 e1e6 f6g4 c3e4 d7f6 e4c3 f6h5 c3e4 h5f6

It's black to play
r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R w KQkq - 0 1

[zullil]

2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R W

The position field might be OK, but the FEN above is invalid. (When I copied it into Stockfish, the engine analyzed the position as if Black were to move!)

This seems better: r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R w KQkq -

Stockfish goes for exd6:

Code: Select all

info depth 30 seldepth 42 score cp 0 nodes 907095890 nps 7552146 time 120111 multipv 1 pv e5d6 e8g8 e1g1 e7d6 a2a4 h5f6 f4f5 d8b6 a4a5 b6c6 f5g6 f7g6 f1e1 a8e8 d4d5 c6a6 e1e6 f6g4 c3e4 d7f6 e4c3 f6h5 c3e4 h5f6

It's black to play

No, it isn't.

[Vinvin]

2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R W

The position field might be OK, but the FEN above is invalid. (When I copied it into Stockfish, the engine analyzed the position as if Black were to move!)

This seems better: r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R w KQkq -

Stockfish goes for exd6:

Code: Select all

info depth 30 seldepth 42 score cp 0 nodes 907095890 nps 7552146 time 120111 multipv 1 pv e5d6 e8g8 e1g1 e7d6 a2a4 h5f6 f4f5 d8b6 a4a5 b6c6 f5g6 f7g6 f1e1 a8e8 d4d5 c6a6 e1e6 f6g4 c3e4 d7f6 e4c3 f6h5 c3e4 h5f6

It's black to play

No, it isn't.

Oops, I forgot 1..Be3
[D]r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N1BN2/PPP3PP/R2QK2R b KQkq - 1 1

[Vinvin]

r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R W

Two very strong engines have recently played Bd3 here, allowing black to play Nxf4.
After Bxf4, dxc4; Ne2, dxe5; the resulting big pawn phalanx has then given black a big advantage.

Stockfish analyze with 5 best moves after 10 min (Intel 3.1 Ghz, 2 cores) agrees 1.Be3 is the best move and 1...Nxf4 is the best reply.

[D] r2qk2r/pp1nppbp/3p2p1/2p1P2n/3P1P2/2N2N2/PPP3PP/R1BQK2R w KQkq - 0 1

Code: Select all

Stockfish_14011911_32bit:
...
 27/43	09:27	 909.472.555	1.601.807	-0,25	dxc5 dxe5 fxe5 Cxe5 De2 Cxf3+ Dxf3 Dd4 Fd2 0-0 0-0-0 Dxc5 g4 Cf6 g5 Cd7 Fe3 Dc7 Cd5 De5 c3 Tae8 h4 e6 Cb4 Db5 Fxa7 Ce5 De3 Cc4 Dd3
 27/43	09:27	 909.472.555	1.601.807	-0,35	Ce2 cxd4 exd6 e5 0-0 0-0 fxe5 Cxe5 Cexd4 Dxd6 c3 Tfe8 Db3 Cxf3+ Cxf3 Cf6 Cd4 Dd5 Fd2 Dxb3 Cxb3 Te2 Tae1 Tae8
 27/43	09:27	 909.472.555	1.601.807	-0,07	exd6 0-0 0-0 exd6 Rh1 Chf6 f5 Db6 Tb1 Tfe8 Ff4 Tad8 fxg6 hxg6 Dd2 cxd4 Cxd4 Ce4 Cxe4 Txe4 c3 Da6 Cf3 Fe5 Cxe5
 27/43	09:27	 909.472.555	1.601.807	-0,04	e6 fxe6 Cg5 Da5 Cxe6 cxd4 Cxg7+ Cxg7 Dxd4 0-0 Fd2 Ce6 Dd5 Dxd5 Cxd5 Cf6 Cxf6+ Txf6 g3 Cd4 0-0 Te6 c3 Te2 Tad1 Ce6 Tf2 Txf2 Rxf2 Rf7 Fe3 b6 Rf3 Tc8 Te1
 27/43	09:27	 909.472.555	1.601.807	 0,00	Fe3 Cxf4 Fxf4 cxd4 e6 fxe6 Cxd4 Fxd4 Dxd4 e5 Fxe5 Cxe5 0-0-0 0-0 Dd5+ Rg7 Dxb7 Te8 The1 Db8 Dxb8 Taxb8 Cd5 Tb7 Cf4 Tbb8 Cd5