Page 1 of 2

Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 9:06 am
by BeyondCritics



This highly theoretical position stems from the Polugaevsky variation of the Najdorf Defence, when white plays 10.exf6 and black defends with 15...Qc7,16...Bb7. It is critical for the 16...Bb7 line.
There are some good moves, but only one move wins. Your task -- if you choose to accept it -- is to show this move. Extra credit for explanations.
Note that Parimarjan Negi, in his highly praised repertoire book about the Najdorf from 2015, failed to show the correct refutation of 16...Bb7. IMHO this demonstrates how fast engine chess is still evolving.

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 10:08 am
by Vinvin
Crystal 1.1 wants to play 23.h3.
20 min on 4*4Ghz. 3 best moves.

Code: Select all

FEN: 1n2k2r/2qr1p2/p3p3/6Np/Pp2Q3/2b5/2P1B1PP/1R3R1K w k - 0 23

Crystal1.1:
...
---------------------------------------------------------------------------
 19/32	00:19	 89.577k	4.662k	+0,38	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Qe5 28.Qxe5 Bxe5 29.Rxh4 Bf6 30.Rh6 Bxg5 31.Rh8+ Ke7 32.Rxb8 Rd4 33.g3 Rxa4 34.Kg2 Kf6 35.Kf3
 19/46	00:19	 89.577k	4.662k	+0,51	23.Qf3 h4 24.Ne4 h3 25.gxh3 Nc6 26.Bxa6 Ne5 27.Qg2 Kf8 28.Nxc3 Qxc3 29.Rb3 Qd4 30.Bc8 Rd6 31.Bb7 Rg8 32.Rg3 Rxg3 33.hxg3 Qc5 34.Qf2 Qxf2 35.Rxf2 Rd7 36.Re2
 19/36	00:19	 89.577k	4.662k	+0,57	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Rf1 h4 28.Qb4+ Ke8 29.Qb3 Be5 30.Qf3 f5 31.Bxa6 Ke7 32.Bb5 Rd2 33.Bd3 Qg4 34.Qb7+ Kf6 35.Qa8
---------------------------------------------------------------------------
 20/57	00:28	 133.355k	4.709k	+0,51	23.Rbd1 Rxd1 24.Rxd1 Bf6 25.h4 Kf8 26.Nh7+ Rxh7 27.Qxh7 Qf4 28.Qd3 Qxh4+ 29.Qh3 Qxh3+ 30.gxh3 Ke7 31.Bxh5 a5 32.Be2 Nc6 33.Bd3 Nd4 34.Rf1 Bg5 35.h4 Bh6 36.Kg2 f5 37.Kh3 Kf6 38.Kg3 Be3
 20/49	00:28	 133.355k	4.709k	+0,59	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Qe5 28.Qxe5 Bxe5 29.Rxh4 Bf6 30.Rg4 Nc6 31.Nf3 Ke7 32.Rc4 Nd4 33.Nxd4 Bxd4 34.g4 Be5 35.Kg2 Rd4 36.Rxd4 Bxd4 37.Bxa6
 20/36	00:28	 133.355k	4.709k	+0,61	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Qb4+ Ke8 28.Bxa6 Rd1+ 29.Bf1 Qe5 30.a5 f5 31.Qc4 Ke7 32.a6 Bf6 33.g3 Qe4 34.Qxe4 fxe4 35.Rf4 Bg5 36.a7 Ra1 37.Rxe4 Rxa7
---------------------------------------------------------------------------
 21/34	00:33	 159.706k	4.729k	+0,44	23.Rbd1 Rxd1 24.Rxd1 Bf6 25.h4 Kf8 26.Nh7+ Rxh7 27.Qxh7 Qf4 28.Qd3 Qxh4+ 29.Qh3 Qxh3+ 30.gxh3 Ke7 31.Bxh5 a5 32.Bf3 Na6 33.Kg2 Nc5 34.Bc6 Bh4 35.Kf3 f5
 21/36	00:33	 159.706k	4.729k	+0,57	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Qe5 28.Qxe5 Bxe5 29.Rxh4 Bf6 30.Rg4 Nc6 31.Nf3 Ke7 32.Rc4 Nd4 33.Nxd4 Rxd4 34.Rxd4 Bxd4 35.Bxa6 Kf6 36.h4
 21/53	00:33	 159.706k	4.729k	+0,78	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Qb4+ Ke8 28.Bxa6 Rd1+ 29.Bf1 Qe5 30.a5 f5 31.a6 Qa1 32.Qc4 Ke7 33.g3 Be5 34.Kg2 Qd4 35.Qxd4 Bxd4 36.Ra3 Rd2+ 37.Kh3
---------------------------------------------------------------------------
 22/52	00:58	 278.632k	4.757k	+0,54	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Bxa6 Qg4 28.Qe2 Rd5 29.Qf2 f5 30.Qa7+ Rd7 31.Qc5+ Kf7 32.Be2 Qd4 33.Qc8 Rd8 34.Qb7+ Rd7 35.Qb3 Qe5 36.Bd3 Bf6 37.g3 Kg7 38.Rf1 Kh7 39.Qb5 Rc7 40.a5 Qxb5
 22/41	00:58	 278.632k	4.757k	+0,59	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Nc6 28.Nxe6 Qg3 29.Ng7+ Kd8 30.Qe8+ Kc7 31.Nf5 Re7 32.Qxe7+ Bxe7 33.Nxg3 Nxb4 34.Nf5 Bd8 35.Kh2 Nxd3 36.cxd3 Kd7 37.g3 hxg3+ 38.Kxg3 Bb6 39.Kg4 Ke6
 22/48	00:58	 278.632k	4.757k	+1,10	23.h3 Rh6 24.Qh4 Bf6 25.Bxh5 Qe5 26.Bxf7+ Rxf7 27.Qxh6 Qxg5 28.Qxg5 Bxg5 29.Rxf7 Kxf7 30.Rxb4 Nd7 31.h4 Be7 32.Rb7 Nc5 33.Ra7 Nxa4 34.h5 Nc3 35.g4 Ne4 36.Kg2 a5 37.c4 a4 38.Rxa4 Nd2 39.Ra7 Nxc4
---------------------------------------------------------------------------
 23/38	01:08	 326.994k	4.786k	+0,62	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Nc6 28.Nxe6 Qg3 29.Ng7+ Kd8 30.Qe8+ Kc7 31.Nf5 Re7 32.Qxe7+ Bxe7 33.Nxg3 Nxb4 34.Nf5 Nxd3 35.cxd3 Bf6 36.g4 hxg3 37.Kg2 Kb6 38.h4 Ka5 39.Kxg3 Kxa4 40.h5 a5
 23/47	01:08	 326.994k	4.786k	+0,83	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Rf1 h4 28.Bxa6 h3 29.gxh3 Bc3 30.Bd3 Qc5 31.Qg2 f5 32.h4 Qb4 33.Qc6 Qb7 34.Qxb7 Rxb7 35.Bb5 Kf6 36.Kg2 Rh7
 23/34	01:08	 326.994k	4.786k	+0,90	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Rxb4 Qxf4 28.Rxf4 Nc6 29.Rc4 Be5 30.Rf1 Rc7 31.Nxf7 Rxf7 32.Rxc6 Rxf1+ 33.Bxf1 Kf7 34.Rxa6 Rb8 35.g4 hxg3 36.Kg2
---------------------------------------------------------------------------
 24/42	02:01	 580.803k	4.776k	+0,53	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Nc6 28.Nxe6 Qe5 29.Qxe5 Nxe5 30.Nc5 Nxd3 31.Rb8+ Rd8 32.Rxd8+ Kxd8 33.Nxd3 Kc7 34.g3 hxg3 35.Kg2 Bh4 36.Ne5 Kd6 37.Nf3 Be7 38.Kxg3 Ke6 39.h4 Bd6+ 40.Kg4
 24/52	02:01	 580.803k	4.776k	+0,76	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Rf1 Be5 28.Bxa6 Bc7 29.Bd3 Qe5 30.Qxe5 Bxe5 31.a5 Rd8 32.g3 h4 33.gxh4 Rd4 34.Kg2 Rxh4 35.h3 Bc3 36.Kg3 Ra4 37.a6
 24/41	02:01	 580.803k	4.776k	+0,92	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qxb7 Rxb7 29.Rbf1 Bc5 30.Nxf7 Rf8 31.Ng5 Rxf3 32.Bxf3 Re7 33.Bg4 Bd6 34.Rd1 Be5 35.Nxe6 Kf7 36.Rf1+ Kg6 37.Nf4+ Kg7 38.Nd5 Rf7 39.Rxf7+ Kxf7 40.Nxb4 Bd6 41.Nd5 Nc6 42.Kg1 Be5
---------------------------------------------------------------------------
 25/50	03:13	 899.135k	4.644k	+0,65	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qxb7 Rxb7 29.Rbf1 Bc5 30.Nxf7 Rf8 31.Ng5 Rxf3 32.Bxf3 Rb6 33.Re1 Ke7 34.Bg4 Rd6 35.Nxe6 Bf2 36.Re4 Rd2 37.Nf4+ Kd6 38.Rxb4 Rxc2 39.Nd3 Nc6 40.Rb7 Ne5 41.Nxf2 Rxf2 42.Rh7 Kc5
 25/57	03:13	 899.135k	4.644k	+0,73	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Nc6 28.Nxe6 Qe5 29.Qxe5 Nxe5 30.Nc5 Rd8 31.Re4 Kf8 32.Rf4 Nxd3 33.Nxd3 Bg5 34.Rg4 Rd5 35.Rc4 Rf5 36.Kh2 Be7 37.Kg1 Bg5 38.g3 hxg3 39.Kg2 Be7 40.Kxg3 a5
 25/55	03:13	 899.135k	4.644k	+0,75	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Bxa6 Qg4 28.Qe1 Qxa4 29.Qf1 Qa1 30.Rxf7+ Kd6 31.Qxa1 Bxa1 32.Rxd7+ Kxd7 33.g3 Bf6 34.h4 e5 35.Kg2 e4 36.Be2 Bd4 37.Bxh5 Ke6 38.Bg4+ Kd5 39.h5
---------------------------------------------------------------------------
 26/53	05:00	 1.355.758k	4.511k	+0,44	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Qd6 28.Rxh4 Rb7 29.c3 Qe5 30.Qxe5 Bxe5 31.Rb4 Rd7 32.Be2 Rd2 33.Bh5 Ke7 34.Nxf7 Bg3 35.Rb1 Nd7 36.Ng5 Nc5 37.Nf3 Rd5 38.Bg4 Ne4 39.Nd4 Nxc3 40.Rb4 Kf6 41.Bxe6 Re5
 26/63	05:00	 1.355.758k	4.511k	+0,52	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Rf1 Be5 28.Bxa6 h4 29.Bd3 h3 30.gxh3 Bc7 31.Qf3 f5 32.Qe2 Rd5 33.Qe1 Qf6 34.Qe3 Qe5 35.Qg5+ Kf8 36.Qg2 Rd7 37.Rg1 Rg7 38.Qxg7+ Qxg7 39.Rxg7
 26/56	05:00	 1.355.758k	4.511k	+0,58	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qxc7 Rxc7 28.Rxb4 Nc6 29.Rc4 Rg8 30.Nxf7 Rxf7 31.Rxc6 Rxf3 32.gxf3 Kd7 33.Rc4 e5 34.c3 Bf2 35.f4 Rg1+ 36.Kh2 exf4 37.Rxf4 Bg3+ 38.Kxg1 Bxf4 39.Bxa6 Kd6 40.Kf2 Be5 41.c4 Bg3+ 42.Ke3 Kc5 43.Kd3 Kb4 44.Bb5
---------------------------------------------------------------------------
 27/43	06:26	 1.724.032k	4.466k	+0,55	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Nc6 28.Nxe6 Qe5 29.Qxe5 Nxe5 30.Nc5 Nxd3 31.Rb8+ Rd8 32.Rxd8+ Kxd8 33.cxd3 Kc7 34.Nxa6+ Kb6 35.Nb4 Ka5 36.Nd5 Be5 37.Kg1 Bd4+ 38.Kf1 Kxa4 39.Ke2 Kb5 40.Ne7 Kc5
 27/53	06:26	 1.724.032k	4.466k	+0,81	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rb7 Rhd8 27.Qc6 Bf6 28.Qxa6 Qd5 29.Rb1 Be5 30.Rbf1 f5 31.Re3 Qc5 32.Rh3 Rh8 33.Rh4 Rd6 34.Qb5 Rd5 35.c4 Qxb5 36.cxb5 Rd2 37.Re1 Rd4 38.Rxh5 Rxa4
 27/54	06:26	 1.724.032k	4.466k	+0,97	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qxb7 Rxb7 29.Rbf1 Bc5 30.Nxf7 Rf8 31.Ng5 Rxf3 32.Bxf3 Rb6 33.Re1 Bf2 34.Re2 Bg3 35.Nxe6 Kf7 36.Nc5 Rd6 37.Re4 Rc6 38.Rc4 Rc7 39.Bh5+ Kg8 40.Be2 a5 41.Ne4 Rxc4 42.Bxc4+ Kg7 43.Nxg3
---------------------------------------------------------------------------
 28/58	11:16	 3.067.854k	4.537k	+0,59	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rb7 Rhd8 27.Qc6 Qe5 28.Rxf7+ Kxf7 29.Rxd7+ Rxd7 30.Qxd7+ Kf6 31.Qd8+ Kf7 32.Qd3 h4 33.Qxa6 Ba5 34.Qb5 Qa1+ 35.Bf1 Bc7 36.Qh5+ Kg7 37.Qg4+ Kf7 38.Qf3+ Ke7 39.Qf2 Ke8 40.h3 Bg3 41.Qe2 Ke7 42.Qc4 Kf6 43.c3 Kf7 44.Qb5
 28/55	11:16	 3.067.854k	4.537k	+0,73	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Nc6 28.Nxe6 Qe5 29.Qxe5 Nxe5 30.Nc5 Rd8 31.Re4 a5 32.Kh2 Rc8 33.Nb3 Kf8 34.Nxa5 Rc3 35.Nc4 Nxd3 36.cxd3 Rxd3 37.a5 Bd8 38.Kg1 Rd1+ 39.Kf2 Ra1 40.Kf3 Bxa5
 28/60	11:16	 3.067.854k	4.537k	+1,10	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qg4 Nc6 29.Ne4 Kf8 30.Qxe6 Re7 31.Qd5 Qd7 32.Qxd7 Rxd7 33.Bxa6 Rh6 34.Rff1 Re7 35.Bd3 Kg7 36.Rf4 Be3 37.Rf5 Rhe6 38.Ng5 Re5 39.Nf3 Rxf5 40.Bxf5 Ne5 41.Rxb4 Nxf3
---------------------------------------------------------------------------
 29/77	15:57	 4.465.918k	4.666k	+0,70	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rb7 Rhd8 27.Qc6 Qe5 28.Rxf7+ Kxf7 29.Rxd7+ Rxd7 30.Qxd7+ Kf6 31.Qd8+ Kf7 32.Qd3 h4 33.Qxa6 Ba5 34.Qb5 Qf4 35.Qc4 Qc1+ 36.Bf1 Bb6 37.g3 hxg3 38.hxg3 Qe3 39.Qf4+ Qxf4 40.gxf4 Ba5 41.Bd3 e5 42.Kg1 exf4 43.Kg2 Bb6 44.Kf3 Kf6
 29/49	15:57	 4.465.918k	4.666k	+0,73	23.Bd3 Rh6 24.Qe3 Rf6 25.Qh3 Qe5 26.Qxh5 Rxf1+ 27.Rxf1 Bd2 28.Nxe6 Qxh5 29.Ng7+ Ke7 30.Nxh5 b3 31.Rb1 bxc2 32.Bxc2 Rc7 33.Bd3 a5 34.h4 Nd7 35.g3 Nc5 36.Rd1 Rd7 37.Rxd2 Nxd3 38.Nf4 Nxf4 39.Rxd7+ Kxd7 40.gxf4 Ke6 41.h5
 29/57	15:57	 4.465.918k	4.666k	+1,15	23.h3 Rh6 24.Qh4 Nc6 25.Bxh5 Bg7 26.Qg4 Ne5 27.Qe2 Bf6 28.Nxe6 Qc4 29.Qxc4 Nxc4 30.Nc5 Rd4 31.g4 Nd2 32.Rbe1+ Kf8 33.Rf5 Kg7 34.Re2 Nb1 35.a5 Nc3 36.Ref2 Rc4 37.R2f3 Ne4 38.Nxe4 Rxe4 39.Rf2 Rc4 40.Kg2 Rc3 41.Kh2
---------------------------------------------------------------------------
 30/73	23:16	 6.945.803k	4.975k	+0,46	23.Bd3 h4 24.h3 Rh6 25.Qe3 Rf6 26.Rxf6 Bxf6 27.Rxb4 Qd6 28.Rxh4 Rb7 29.c3 Nd7 30.Ne4 Rb1+ 31.Bxb1 Qd1+ 32.Qg1 Qxg1+ 33.Kxg1 Bxh4 34.g3 Be7 35.Bd3 f5 36.Nd2 Nc5 37.Bc2 Bf6 38.c4 Kf7 39.Kf2 Be5 40.g4 Bf4 41.Nf1 fxg4 42.hxg4 Kf6 43.Kf3 Kg5 44.Ne3 Bxe3 45.Kxe3 Kxg4
 30/82	23:16	 6.945.803k	4.975k	+0,53	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rxh8 Bxh8 27.Bxa6 Qg4 28.Qc6 Be5 29.Rxf7+ Kxf7 30.Qxd7+ Kf6 31.Qd2 Qxa4 32.Qh6+ Ke7 33.Qg5+ Kd6 34.Qd8+ Kc5 35.Qe7+ Bd6 36.Qa7+ Kb4 37.Qd4+ Ka5 38.Qxa4+ Kxa4 39.g3 Kb4 40.Be2 e5 41.Bxh5 Kc3 42.Kg2 e4 43.Bg4 Bc5 44.h4
 30/58	23:16	 6.945.803k	4.975k	+1,13	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qg4 Nc6 29.Ne4 Kf8 30.Qxe6 Re7 31.Qd5 Qd7 32.Qxd7 Rxd7 33.Bxa6 Rh6 34.Bd3 Re7 35.Rf5 Re5 36.Rf4 Re7 37.Ng5 Be5 38.Rf5 Nd4 39.Rff1 Nc6 40.Rbe1 f6 41.Nf3 Bg3 42.Rxe7 Kxe7 43.Be4 f5 44.Bxf5

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 10:30 am
by Vinvin
An old Stockfish switch to h3 after 1m56s (4*4GHz).

Code: Select all

FEN: 1n2k2r/2qr1p2/p3p3/6Np/Pp2Q3/2b5/2P1B1PP/1R3R1K w k - 0 23

Stockfish_19091601_x64_bmi2:

 34/18-	01:24	 491.788k	5.818k	+0,90	23.Qf3 h4
 34/18-	01:36	 558.806k	5.780k	+0,79	23.Qf3 h4
 34/51+	01:56	 669.587k	5.766k	+0,90	23.h3
 34/55+	02:06	 733.882k	5.792k	+1,11	23.h3
 34/56	02:18	 808.253k	5.820k	+0,91	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qxb7 Rxb7 29.Rbf1 Bc5 30.Nxf7 Rf8 31.Ng5 Rxf3 32.Bxf3 Re7 33.Bg4 Kd7 34.Nxe6 Kc6 35.a5 Bd6 36.Nd4+ Kc5 37.Nf5 Re4 38.Nxh4 Nc6 39.Ng6 Bg3 40.Bf5 Re1 41.Rxe1 Bxe1 42.Bd3 Bc3 43.Bxa6
 35/54+	02:25	 848.886k	5.839k	+1,01	23.h3
 35/56+	02:29	 870.787k	5.840k	+1,12	23.h3
 35/61+	02:32	 894.165k	5.852k	+1,28	23.h3
 35/61	02:34	 906.656k	5.858k	+1,31	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qg4 Nc6 29.Nh7 Qc7 30.Nf6+ Bxf6 31.Rxf6 Qg3 32.Qe4 Qc3 33.Rbf1 Rd4 34.Rxe6+ fxe6 35.Qxe6+ Kd8 36.Qf6+ Kc7 37.Qxh8 Qxc2 38.Bg4 Kb6 39.Bf3 Rd6 40.Qxh4 Qc5 41.Qf4 Qe5 42.Bxc6 Qxf4 43.Rxf4 Rxc6 44.Rxb4+ Ka5
 36/28-	02:43	 960.884k	5.894k	+1,21	23.h3 h4
 36/45+	02:51	 1.017.576k	5.930k	+1,31	23.h3
 36/63+	02:56	 1.052.519k	5.950k	+1,47	23.h3
 36/75	03:21	 1.220.578k	6.044k	+1,49	23.h3 Qc5 24.Qf4 Qc7 25.Qf3 Rd5 26.Ne4 Rf5 27.Qe3 Be5 28.Rxf5 exf5 29.Nf6+ Kf8 30.Nd5 Qd6 31.Nxb4 Qd4 32.Qxd4 Bxd4 33.Rd1 Bc5 34.Nxa6 Nxa6 35.Bxa6 Rh6 36.Bd3 Bb4 37.Rf1 Re6 38.Rxf5 Re1+ 39.Kh2 h4 40.g3 hxg3+ 41.Kxg3 Ra1 42.Bb5 Bc3 43.Kg4 Ra2 44.Bc6 Rxc2 45.Be4
 37/62-	03:28	 1.257.277k	6.039k	+1,38	23.h3 Qc5
 37/62-	03:35	 1.297.804k	6.034k	+1,27	23.h3 Qc5
 37/62-	03:40	 1.329.696k	6.039k	+1,12	23.h3 Qc5
 37/62+	03:44	 1.358.488k	6.043k	+1,25	23.h3
 37/67	03:51	 1.395.814k	6.034k	+1,30	23.h3 Qc5 24.Qf4 Qc7 25.Qf3 Rd5 26.Ne4 Rf5 27.Qe3 Be5 28.Rxf5 exf5 29.Nf6+ Kf8 30.Nd5 Qd6 31.Nxb4 Qd4 32.Qxd4 Bxd4 33.Rd1 Bc5 34.Nxa6 Nxa6 35.Bxa6 Rh6 36.Bd3 Bb6 37.Bxf5 h4 38.Bd3 Re6 39.Rb1 Ba5 40.Rb8+ Re8 41.Rxe8+ Kxe8 42.g3 hxg3 43.h4 Ke7 44.Kg2 Kf6 45.Kxg3 Be1+ 46.Kg4 Bd2 47.h5 Kg7 48.Kf5
 38/61-	03:58	 1.436.321k	6.034k	+1,19	23.h3 Qc5
 38/61+	04:05	 1.481.750k	6.039k	+1,30	23.h3
 38/64	04:11	 1.518.280k	6.044k	+1,25	23.h3 Qc5 24.Qf4 Qc7 25.Qf3 Rd5 26.Ne4 Rf5 27.Qe3 Be5 28.Rxf5 exf5 29.Nf6+ Kf8 30.Nd5 Qd6 31.Nxb4 Qd4 32.Qxd4 Bxd4 33.Rd1 Bc5 34.Nxa6 Nxa6 35.Bxa6 Rh6 36.Bd3 Bb4 37.Rb1 Rb6 38.g3 f4 39.gxf4 Ba5 40.Rxb6 Bxb6 41.Kg2 Ba5 42.Be2 h4 43.Kf3 Ke7 44.Ke4 Ke6 45.Kd4 Kf5 46.Kc4 Bc7 47.Kb5 Bxf4 48.a5 Be3 49.Bc4 f6 50.Bd3+ Kf4 51.a6
 39/58+	04:19	 1.571.479k	6.056k	+1,36	23.h3
 39/65	04:28	 1.629.157k	6.071k	+1,28	23.h3 Qc5 24.Qf4 Qc7 25.Qf2 Rd5 26.Ne4 Rf5 27.Qe3 Be5 28.Rxf5 exf5 29.Nf6+ Kf8 30.Nd5 Qd6 31.Nxb4 Qd4 32.Qxd4 Bxd4 33.Rd1 Bc5 34.Nxa6 Nxa6 35.Bxa6 Rh6 36.Bd3 Bb4 37.Rb1 Rb6 38.Rf1 Rf6 39.g3 f4 40.Kg2 Bd2 41.gxf4 Ke7 42.Kg3 Rd6 43.Kh4 Rd4 44.a5 Bxa5 45.Kxh5 Kf8 46.Kg5 Bc3 47.Kg4 Ra4
 40/51+	04:34	 1.667.155k	6.083k	+1,39	23.h3
 40/56+	04:52	 1.783.578k	6.103k	+1,50	23.h3
 40/69	05:06	 1.862.948k	6.082k	+1,37	23.h3 Qc5 24.Qf4 Qc7 25.Qf3 Rd5 26.Ne4 Rf5 27.Qe3 Be5 28.Rxf5 exf5 29.Nf6+ Kf8 30.Nd5 Qd6 31.Nxb4 Qd4 32.Qxd4 Bxd4 33.Rd1 Bc5 34.Nxa6 Nxa6 35.Bxa6 Rh6 36.Bd3 Bb6 37.Rf1 Rf6 38.g3 f4 39.gxf4 Ba5 40.Kg2 Rd6 41.Kf3 Rd4 42.Ra1 Ke7 43.Ke3 Rb4 44.h4 Ke6 45.c4 Rb2 46.Kd4 Rh2 47.Kc5 Rxh4 48.Kb5 Rh3 49.c5 Rxd3
 41/72-	05:58	 2.188.358k	6.106k	+1,26	23.h3 Rh6
 41/72-	06:34	 2.416.340k	6.129k	+1,15	23.h3 Rh6
 41/72+	06:55	 2.552.111k	6.135k	+1,26	23.h3
 41/72+	07:06	 2.613.922k	6.134k	+1,48	23.h3
 41/74	07:15	 2.670.973k	6.137k	+1,40	23.h3 Rh6 24.Qh4 Qe5 25.Ne4 Bd4 26.Bc4 Bb6 27.Nf6+ Rxf6 28.Qxf6 Qxf6 29.Rxf6 Rd4 30.Be2 Nd7 31.Rf3 Ke7 32.Bxa6 Nc5 33.c3 Rd2 34.Rxb4 Ba5 35.Bb5 Rd1+ 36.Kh2 f5 37.Rh4 Bc7+ 38.g3 Rd2+ 39.Kg1 Ne4 40.Rxh5 Bxg3 41.Rh7+ Kf6 42.Rh6+ Kg7 43.Rxe6 Bh2+ 44.Kf1 Ng5 45.Ree3 Nxf3 46.Rxf3 Ra2 47.Rxf5 Kg6 48.Rd5 Ra3 49.Rc5 Bf4 50.Kg2 Be3 51.Rc6+ Kg5

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 10:39 am
by Vinvin
Current Stockfish switches to h3 after 3m12s (4*4GHz).

Code: Select all

Stockfish_19112810_x64_modern:
Found 145 tablebases
...
 34/52+	02:00	 737.080k	6.133k	+0,92	23.Rbd1
 34/63	02:07	 784.496k	6.134k	+0,72	23.Rf3 Qe5 24.Rxb4 Qxg5 25.Rxb8+ Ke7 26.Rb1 Qe5 27.Qh4+ f6 28.Bd3 Rd4 29.Qf2 Rhd8 30.Rg3 R8d7 31.Qf3 Rg4 32.Rxg4 hxg4 33.Qxg4 f5 34.Qg5+ Qf6 35.Qh5 Qh8 36.Qxh8 Bxh8 37.Bxa6 Bc3 38.Bb5 Rd8 39.Rf1 Rd4 40.g3 Kf6 41.Kg2 Rd2+ 42.Rf2 Rxf2+ 43.Kxf2 Ba5 44.Kg2 e5 45.h4 e4 46.Kf2 Kg7 47.Ke2 Bc7 48.a5 Bxa5
 35/52-	02:26	 899.540k	6.143k	+0,61	23.Rf3 Qe5
 35/59+	02:41	 990.540k	6.152k	+0,72	23.Rbd1
 35/59+	02:41	 996.248k	6.154k	+0,87	23.Rbd1
 35/65-	02:49	 1.043.011k	6.156k	+0,51	23.Rbd1 Rxd1
 35/65+	03:12	 1.180.057k	6.146k	+0,79	23.h3
 35/65+	03:38	 1.347.005k	6.166k	+1,17	23.h3
 35/65	03:49	 1.414.013k	6.171k	+1,26	23.h3 h4 24.Rf3 Qc6 25.Qe3 Bd4 26.Qf4 Qc7 27.Qe4 Qb7 28.Qg4 Nc6 29.Ne4 Kf8 30.Qxe6 Re7 31.Qf5 Qd7 32.Qxd7 Rxd7 33.Bxa6 Rh6 34.Bc4 Rc7 35.Rf5 Ne5 36.Bb5 Nc4 37.Rxb4 Ne3 38.Rf3 Nxc2 39.Rc4 Rxc4 40.Bxc4 Ne3 41.Bb5 Kg7 42.Ng5 Kg6 43.Nxf7 Rh5 44.Bd3+ Kg7
 36/45-	03:51	 1.426.274k	6.171k	+1,15	23.h3 h4
 36/58+	03:58	 1.469.971k	6.167k	+1,26	23.h3
 36/58+	04:03	 1.499.624k	6.167k	+1,42	23.h3
 36/68-	04:18	 1.595.566k	6.177k	+1,05	23.h3 Rh6
 36/70+	04:23	 1.626.558k	6.180k	+1,34	23.h3

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 11:21 am
by zullil
BeyondCritics wrote:
Fri Nov 29, 2019 9:06 am



This highly theoretical position stems from the Polugaevsky variation of the Najdorf Defence, when white plays 10.exf6 and black defends with 15...Qc7,16...Bb7. It is critical for the 16...Bb7 line.
There are some good moves, but only one move wins. Your task -- if you choose to accept it -- is to show this move. Extra credit for explanations.
Note that Parimarjan Negi, in his highly praised repertoire book about the Najdorf from 2015, failed to show the correct refutation of 16...Bb7. IMHO this demonstrates how fast engine chess is still evolving.
Lc0 (network J13B.3-200) with 100M nodes suggests Bd3 is best:

1129 06:13:10.492107 140174937810688 ../../src/mcts/search.cc:384] Stopped search: Reached visits limit: 100000235>=100000000

1129 06:13:10.495849 140174937810688 ../../src/chess/uciloop.cc:218] << info depth 42 seldepth 98 time 5508878 nodes 100000235 score cp 73 hashfull 271 nps 18130 tbhits 2387 multipv 1 pv e2d3 h5h4 h2h3 h8h6 e4e3 c3d4 e3d2 d4c3 d2e3 c3d4 e3c1 h6f6 b1b4 f6f1 c1f1 b8c6 b4c4 c7b6 g5f3 d4f6 c4f4 b6d8 f1e1 d7d5 e1f1 d5d7 f1e1 d7d5 e1f2 d8e7 f3h4 f6e5 f4g4 e5d4 f2f4 d4e5 f4f2 e5d4 f2f4 d4e5 f4e3 e5c7 h4f3 e7d6 g2g3 c6b4 d3e4 d5d1 h1h2 b4d5 e4d5 d1d5 h3h4 d6c6 f3d4 c6a4 c2c4 a4c4 d4e6 c4c2 h2h3 d5e5 e6g7 e8e7 e3f3 c2c5 h4h5 c5d5 f3d5 e5d5 h5h6 d5d8 h3h4 c7e5 g4e4 e7f6 g3g4 d8d5 h4h5 e5b2 g7f5 d5d1 f5h4 d1d5 h4f5 d5d1

More:
Nodes: 100M, N/s: 18.1k, Time: 1h 31m (limit met)

62.5% Bd3 h4 h3 Rh6 Qe3 Bd4 Qd2 Bc3 Qe3 Bd4 Qc1 Rf6 Rxb4 Rxf1+ Qxf1 Nc6 Rc4 Qb6 Nf3 Bf6 Rf4 Qd8 Qe1 Rd5 Qf1 Rd7 Qe1 Rd5 Qf2 Qe7 Nxh4 Be5 Rg4 Bd4 Qf4 Be5 Qf2 Bd4 Qf4 Be5 Qe3 Bc7 Nf3 Qd6 g3 Nb4 Be4 Rd1+ Kh2 Nd5 Bxd5 Rxd5 h4 Qc6 Nd4 Qxa4 c4 Qxc4 Nxe6 Qc2+ Kh3 Re5 Ng7+ Ke7 Qf3 Qc5 h5 Qd5 Qxd5 Rxd5 h6 Rd8 Kh4 Be5 Re4 Kf6 g4 Rd5 Kh5 Bb2+ Nf5 Rd1 Nh4 Rd5+ Nf5 Rd1 (N: 98.2M, P: 4.61%)

61.0% Rf3 Qe5 Rxb4 Qxg5 Rxb8+ Ke7 Rxh8 Bxh8 Qb4+ Ke8 Bxa6 Rd1+ Bf1 f5 a5 Qc1 Qc4 Ke7 a6 Bd4 h4 Kf6 c3 Be5 a7 Qa3 Qe2 Ra1 Qd2 Qxa7 Qg5+ Kf7 Qxh5+ Kf8 Qh6+ Kf7 Qh5+ Kf8 (N: 473k, P: 5.14%)

58.7% Nxf7 Rxf7 Qg6 Nc6 Bxh5 Nd8 Rbd1 Qc5 Qd3 Qc7 Qg6 Qc5 Qd3 Qc7 Qxd8+ Qxd8 Rxd8+ Kxd8 Bxf7 Rf8 Rd1+ Ke7 Bg6 a5 Kg1 Rb8 Rd3 b3 cxb3 Rxb3 h4 Ra3 Kh2 Be5+ Kh3 Rxa4 Rf3 Rf4 Ra3 a4 Bc2 (N: 254k, P: 9.66%)

58.4% Rbd1 Rxd1 Bxd1 Qe5 Qxe5 Bxe5 Nxf7 Rf8 Bxh5 Ke7 Rf3 Bd4 Ng5 Rc8 Rf7+ Kd6 Bd1 Nd7 h4 Nc5 a5 Be3 Kh2 Bxg5 hxg5 Rg8 Rf4 Rxg5 Rxb4 Nd7 Ra4 Rc5 Be2 Nb8 Bd3 Nc6 g4 Ke7 Kg3 Nxa5 Kh4 Nc6 (N: 225k, P: 9.22%)

61.2% h3 h4 Bd3 Re7 Rbd1 f5 Qe3 Rh6 Ne4 Bg7 Nc5 Qe5 Qf2 Qg3 Qg1 Bc3 Rf3 Qe5 Nxa6 Nxa6 Bxa6 Kf7 Bc4 Kg7 Qf2 Qc7 Bb3 Be5 Qd2 Bc3 Qe2 Rg6 (N: 192k, P: 1.64%)

59.9% Qf3 h4 Ne4 h3 gxh3 Nc6 Bxa6 Ne5 Qg2 Kf8 Bb5 Rd5 Ng5 Ke7 Ne4 Kf8 Rbd1 Rg8 Ng3 Rxd1 Rxd1 Qb6 Qa8+ Kg7 Nh5+ Kh8 Qe4 f5 Qf4 Qb7+ Rd5 Qxd5+ (N: 142k, P: 3.67%)

56.3% h4 Rd4 Rxf7 Rxe4 Rxc7 Rxh4+ Nh3 Be5 Rb7 Rg8 R1xb4 Rxb4 Rxb4 Ke7 Rb7+ Kd6 Nf2 Rc8 Ne4+ Kd5 Bd3 h4 Kg1 Rf8 Rh7 Rf4 Ng5 Rxa4 c4+ (N: 89.3k, P: 5.51%)

59.7% Rf4 Qe5 Rxb4 Qxg5 Rxb8+ Ke7 Rxh8 Bxh8 Qb4+ Ke8 Bxa6 Bc3 Qb8+ Ke7 Rf1 Be5 Qb4+ Bd6 Qe4 Qe5 Qh4+ Kf8 Re1 Qc3 Bd3 Bc7 Rf1 Qe5 g3 Rd4 Qf6 Qxf6 Rxf6 h4 Kg2 Rxa4 (N: 87.0k, P: 2.38%)

51.9% Qh4 Qe5 Ne4 Rd4 Nf6+ Kd8 Ng4+ Ke8 Nf6+ Kd8 Ng4+ Ke8 Nf6+ Kd8 (N: 59.4k, P: 6.29%)

55.1% Rf2 Qc5 Qf4 Be5 Qh4 Rd4 Qh3 Rg4 Rxf7 Qxc2 Re1 Qc3 Qxc3 Bxc3 Bxg4 Bxe1 Rb7 Nc6 Bxe6 Nd8 Rb8 Ke7 Bc4 Rh6 g3 Rc6 Be2 h4 Kg2 hxg3 hxg3 (N: 40.2k, P: 2.95%)

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 12:33 pm
by BeyondCritics
The alleged solution was indeed 23.h3! and still i believe this is best.
23.Bd3 comes as a surprise but the leela line looks not convincing to me. Only a pawn with some compensation for black, seems to be between somewhat better and clearly better for white.
Still i think it is remarkable that in the polugaevsky in the midst of a skirmish a slow move like h3 can be viable. The fact that leela doesn't like that move underlines this only.

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 1:38 pm
by Vinvin
On recent 16 cores, current SF should find h3 in less than 30 sec.
Why did you post it as a "challenge" ?

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 2:44 pm
by BeyondCritics
Vinvin wrote:
Fri Nov 29, 2019 1:38 pm
On recent 16 cores, current SF should find h3 in less than 30 sec.
Why did you post it as a "challenge" ?
I believe you are just a patzer.
If you choose to play the ignorant, this is fine for me.

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 9:26 pm
by Dicaste
Best move is Rf3. Best moves sorted are:
  • Rf3
  • Bd3
  • h3
  • Qf3

Re: Polugaevsky Variation, 10.exf6, 16...Qc7, 16...Bb7

Posted: Fri Nov 29, 2019 10:39 pm
by jdart
It looks like the whole variation with 7. .. b5 is being avoided recently. A search for games in Correspondence DB for players >=2250 found 5 games 2017-2019 and all were White wins. OTB players are trying it more often and are more successful but it looks like if White follows the best line Black is in difficulties.

--Jon