Queen and pawn endgame

[zullil]

or maybe stockfish simply cannot find the win in a pawn endgame.
Did not check if b4 is the only winning move

[d]8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38 bm b4

Latest asmFish can find b4, so surely Stockfish will too.

Code: Select all

info depth 43 seldepth 50 multipv 1 time 30982 nps 70710489 score cp 0 nodes 2190752398 tbhits 0 hashfull 145 pv d3e3 f7f5 e3f4 f5g4 f4g4 h7g7 a2a4 g6h5 g4h5 a7a5 c2c3 g7f6 b2b4 a5b4 c3b4 f6e5 a4a5 e5d5 b4b5 d5c5 a5a6 b7a6 b5a6 c5b6 a6a7 b6a7 h5g6 h6h5 g6g5 a7b6 g5f4 b6a6 f4f3 a6b5 f3f4 b5a6
info depth 44 currmove d3e3 currmovenumber 1
info depth 44 currmove h5g6 currmovenumber 2
info depth 44 currmove d3e4 currmovenumber 3
info depth 44 currmove c2c4 currmovenumber 4
info depth 44 currmove a2a4 currmovenumber 5
info depth 44 currmove b2b4 currmovenumber 6
info depth 44 seldepth 50 multipv 1 time 59142 nps 71668168 score cp 7 lowerbound nodes 4238598822 tbhits 0 hashfull 308 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 62530 nps 71477333 score cp 14 lowerbound nodes 4469477655 tbhits 0 hashfull 331 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 64836 nps 71393852 score cp 25 lowerbound nodes 4628891838 tbhits 0 hashfull 346 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 66376 nps 71438851 score cp 40 lowerbound nodes 4741825215 tbhits 0 hashfull 354 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 68620 nps 71377407 score cp 61 lowerbound nodes 4897917682 tbhits 0 hashfull 365 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 70602 nps 71446546 score cp 89 lowerbound nodes 5044269079 tbhits 0 hashfull 371 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 72766 nps 71449291 score cp 127 lowerbound nodes 5199079180 tbhits 0 hashfull 377 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 75108 nps 71481010 score cp 175 lowerbound nodes 5368795754 tbhits 0 hashfull 390 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 77706 nps 71726407 score cp 237 lowerbound nodes 5573572243 tbhits 0 hashfull 394 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 82051 nps 71931424 score cp 317 lowerbound nodes 5902045348 tbhits 0 hashfull 406 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 88173 nps 72685179 score cp 419 lowerbound nodes 6408870344 tbhits 0 hashfull 426 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 97930 nps 74597062 score cp 548 lowerbound nodes 7305290352 tbhits 0 hashfull 460 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 108381 nps 75959788 score cp 711 lowerbound nodes 8232597850 tbhits 0 hashfull 484 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 135651 nps 79064144 score cp 917 lowerbound nodes 10725130221 tbhits 0 hashfull 558 pv b2b4

[Rodolfo Leoni]

or maybe stockfish simply cannot find the win in a pawn endgame.
Did not check if b4 is the only winning move

[d]8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38 bm b4

Here, latest Andscacs beta (without any TBs support) finds b4 quickly enough. It takes just a bit more to score it as a winning move.

[d]8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38

Code: Select all

FEN: 8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38

Andscacs091150:
 8/13	00:00	 5k	1,033k	-0.36	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6
 8/10	00:00	 8k	1,301k	-0.34	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Ke5
 9/14	00:00	 6k	1,035k	-0.39	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5
 9/9	00:00	 7k	1,100k	-0.39	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5
 10/14	00:00	 7k	1,211k	-0.33	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Ke5
 10/9	00:00	 8k	1,095k	-0.33	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Ke5
 11/17	00:00	 9k	1,229k	-0.33	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Ke5 45.Kh5
 11/10	00:00	 9k	1,315k	-0.33	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Ke5 45.Kh5
 12/16	00:00	 12k	1,455k	-0.29	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Kg6 45.a4 Kf6
 12/11	00:00	 12k	1,537k	-0.29	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Kg6 45.a4 Kf6
 13/20	00:00	 15k	1,655k	-0.29	38.Ke3 f5 39.Kf4 fxg4 40.Kxg4 Kg7 41.c4 Kf6 42.hxg6 Kxg6 43.b4 Kf6 44.c5 Kg6 45.a4 Kf6 46.Kh5
 14/25+	00:00	 37k	3,099k	+0.03	38.b4 f5 39.c4 fxg4 40.c5 a6 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.Ke3 h3
 14/25+	00:00	 65k	3,809k	+0.39	38.b4 f5 39.c4 fxg4 40.c5 a6 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.Ke3 h3
 14/35	00:00	 102k	4,246k	 0.00	38.b4 f5 39.c4 a6 40.c5 fxg4 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.c6 bxc6 45.bxc6 h3 46.c7 h2 47.c8Q h1Q 48.Qd7+ Kg6 49.Qxg4+ Kf7
 15/34+	00:00	 156k	5,389k	+0.16	38.b4 f5 39.c4 a6 40.c5 fxg4 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.Ke3 h3 45.Kf2
 15/33+	00:00	 162k	5,391k	+0.40	38.b4 f5 39.c4 a6 40.c5 fxg4 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.Ke3 h3 45.Kf2
 15/36	00:00	 171k	5,339k	+0.26	38.b4 f5 39.c4 a6 40.c5 fxg4 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.Ke3 h3 45.Kf2 h2 46.Kg2 h1Q+ 47.Kxh1 Kg7 48.c6 bxc6 49.bxc6 Kf6 50.c7
 16/28+	00:00	 174k	5,286k	+0.42	38.b4 f5 39.c4 a6 40.c5 fxg4 41.a4 gxh5 42.b5 axb5 43.axb5 h4 44.Ke3 h3 45.Kf2 h2
 16/39	00:00	 269k	4,346k	+0.20	38.b4 f5 39.c4 a6 40.c5 Kg7 41.hxg6 fxg4 42.a4 h5 43.b5 axb5 44.axb5 h4 45.c6 bxc6 46.bxc6 h3 47.c7 h2 48.c8Q h1Q 49.Qd7+ Kf6 50.Qd4+ Kf5
 16	00:00	 202k	3,208k	+0.20	38.b4 f5 39.c4 a6 40.c5 Kg7 41.hxg6 fxg4 42.a4 h5 43.b5 axb5 44.axb5 h4 45.c6 bxc6 46.bxc6 h3 47.c7 h2 48.c8Q h1Q 49.Qd7+ Kf6 50.Qd4+ Kf5
 17/37+	00:00	 278k	4,270k	+0.36	38.b4 f5 39.c4 a6 40.c5 Kg7 41.hxg6 fxg4 42.a4 h5 43.b5 axb5 44.axb5 h4 45.Ke3 h3 46.Kf2
 17/30+	00:00	 289k	4,019k	+0.52	38.b4 f5 39.c4 a6 40.c5 Kg7 41.hxg6 fxg4 42.a4 h5 43.b5 axb5 44.axb5 h4 45.Ke3 h3 46.Kf2
 18/27	00:00	 1,013k	3,883k	+0.50	38.b4 a6 39.c4 Kg7 40.c5 Kf6 41.Ke4 Kg5 42.hxg6 fxg6 43.a4 h5 44.gxh5 gxh5 45.b5 axb5 46.axb5 h4 47.Kf3 h3 48.Kg3 Kf6 49.Kxh3 Ke7
 19	00:01	 3,285k	3,134k	+0.66	38.b4 Kg7 39.c4 Kf6 40.Ke4 Kg5 41.c5 a6 42.hxg6 fxg6 43.a4 h5 44.gxh5 gxh5 45.b5 axb5 46.axb5 h4 47.Kf3 h3 48.Kg3 Kf5 49.c6 bxc6 50.b6
 20/44	00:01	 4,022k	3,189k	+0.65	38.b4 Kg7 39.c4 Kf6 40.Ke4 a6 41.c5 Ke7 42.Ke5 f5 43.gxf5 gxh5 44.Kf4 h4 45.a4 h3 46.Kg3 Kf6 47.b5 axb5 48.axb5 Kxf5 49.c6 h2 50.Kxh2 bxc6 51.b6
 20/20	00:01	 3,804k	3,014k	+0.65	38.b4 Kg7 39.c4 Kf6 40.Ke4 a6 41.c5 Ke7 42.a3 f5+ 43.gxf5 gxh5 44.Kf4 Kf6 45.a4 h4 46.b5 h3 47.Kg3 axb5 48.axb5 Kxf5 49.c6 h2 50.Kxh2 bxc6 51.b6
 21/39	00:05	 17,005k	3,070k	+0.64	38.b4 Kg7 39.c4 Kf6 40.Ke4 a6 41.c5 Ke7 42.a4 gxh5 43.gxh5 Ke6 44.b5 a5 45.b6 Kd7 46.Kd5 f6 47.c6+ bxc6+ 48.Kd4 Kd6 49.Ke4 c5 50.b7 Kc7
 22/32+	00:05	 17,049k	3,021k	+0.80	38.b4 Kg7 39.c4 Kf6 40.Ke4 a6 41.c5 Ke7 42.a4 gxh5 43.gxh5 Ke6 44.b5 a5 45.b6 f5+ 46.Kf4 Kd5 47.Kxf5 Kxc5 48.Kg6 Kb4
 22/40+	00:06	 19,027k	3,004k	+1.20	38.b4 Kg7 39.c4 Kf6 40.Ke4 a6 41.a4 Ke7 42.Ke5 f6+ 43.Kf4 gxh5 44.gxh5 Ke6 45.Ke4 f5+ 46.Kf4 Kf6 47.c5 Ke6 48.a5 Kd5
 22/42+	00:06	 20,129k	2,933k	+1.56	38.b4 Kg7 39.c4 Kf6 40.Ke4 a6 41.a4 b6 42.c5 bxc5 43.bxc5 gxh5 44.gxh5 a5 45.Kd5 Ke7 46.Kc6 f5 47.Kb6 f4 48.c6 f3
 23/42	00:10	 29,510k	2,919k	+2.10	38.b4 Kg7 39.c4 a6 40.c5 Kf8 41.a4 Ke7 42.Kd4 Ke6 43.Ke4 Ke7 44.Ke5 f6+ 45.Ke4 f5+ 46.gxf5 gxh5 47.Ke5 Kd8 48.b5 h4 49.Kf4 axb5 50.axb5 h3 51.Kg3 h2 52.Kxh2 Kd7 53.Kh3 h5
 23	00:10	 29,278k	2,896k	+2.10	38.b4 Kg7 39.c4 a6 40.c5 Kf8 41.a4 Ke7 42.Kd4 Ke6 43.Ke4 Ke7 44.Ke5 f6+ 45.Ke4 f5+ 46.gxf5 gxh5 47.Ke5 h4 48.Kf4 Kd8 49.Kg4 Ke8 50.b5 h5+ 51.Kxh4 axb5 52.axb5 Ke7
 24/45+	00:12	 30,674k	2,487k	+2.26	38.b4 Kg7 39.c4 a6 40.c5 Kf8 41.a4 Ke7 42.Kd4 f5 43.gxf5 gxh5 44.Ke4 Kf6 45.Kf4 h4 46.b5 axb5 47.axb5 h3 48.Kg3 Ke5 49.Kxh3 Kd5
 24/43+	00:14	 37,040k	2,579k	+2.42	38.b4 Kg7 39.c4 Kf6 40.Ke4 Ke7 41.c5 Kf6 42.Kd5 Ke7 43.b5 a5 44.bxa6 bxa6 45.g5 hxg5 46.h6 g4 47.h7
 24/45+	00:17	 44,731k	2,582k	+2.66	38.b4 Kg7 39.c4 Kf6 40.Ke4 Ke7 41.c5 a6 42.Ke5 f5 43.gxf5 gxh5 44.a4 h4 45.Kf4 h3 46.Kg3 h2 47.Kxh2 Kf6 48.b5 axb5 49.axb5 Ke5
 24/44	00:20	 54,505k	2,637k	+2.89	38.b4 b5 39.c4 bxc4+ 40.Kxc4 f5 41.gxf5 gxh5 42.Kd3 h4 43.Ke4 Kg7 44.b5 Kf6 45.a4 h3 46.Kf3 Ke5 47.a5 h5 48.b6 axb6 49.axb6 Kd6 50.Kg3 Kc6 51.f6 Kxb6 52.f7 h4+ 53.Kxh3
 25/41	00:21	 57,027k	2,641k	+3.02	38.b4 gxh5 39.gxh5 Kg7 40.c4 Kf6 41.Ke4 b6 42.Kd5 Ke7 43.Ke5 a6 44.c5 bxc5 45.bxc5 a5 46.c6 a4 47.c7 Kd7 48.Kf6 Kxc7 49.Kxf7 Kd6 50.Kg6 Ke7 51.Kxh6 Kf7 52.Kh7 Kf6 53.h6
 26/45	00:24	 64,725k	2,642k	+3.02	38.b4 f5 39.c4 Kg7 40.c5 gxh5 41.gxh5 Kf6 42.Ke3 Ke5 43.b5 Kd5 44.c6 bxc6 45.bxc6 Kxc6 46.Kf4 Kd7 47.Kxf5 Ke8 48.Kg6 a6 49.Kxh6 Kf7 50.Kh7 Kf6 51.h6 Kf7 52.a3 Kf6 53.a4 Kg5
 26/25	00:24	 63,253k	2,582k	+3.02	38.b4 f5 39.c4 Kg7 40.c5 gxh5 41.gxh5 Kf6 42.Ke3 Ke5 43.b5 Kd5 44.c6 bxc6 45.bxc6 Kxc6 46.Kf4 Kd7 47.Kxf5 Ke8 48.Kg6 a6 49.Kxh6 Kf7 50.Kh7 Kf6 51.h6 Kf7 52.a3 Kf6 53.a4 Kg5
 27/57	00:29	 79,472k	2,680k	+3.18	38.b4 gxh5 39.gxh5 Kg7 40.c4 Kf6 41.Ke4 Kg5 42.c5 Kf6 43.Kd5 a6 44.a4 Ke7 45.Ke5 Kd7 46.Kf6 Ke8 47.b5 a5 48.b6 Kd7 49.Kxf7 Kc6 50.Kg6 Kxc5 51.Kxh6 Kb4 52.Kg7 Kxa4 53.h6 Kb5 54.h7 Kxb6
 28/39	00:32	 85,501k	2,654k	+3.11	38.b4 Kg7 39.c4 f5 40.c5 gxh5 41.gxh5 Kf6 42.Ke3 Ke5 43.b5 Kd5 44.Kf4 Kxc5 45.Kxf5 Kd6 46.Kg6 Ke6 47.Kxh6 Kf7 48.Kh7 Kf6 49.h6 Kf7 50.a3 Kf8 51.Kg6 Kg8 52.a4 Kh8 53.a5 a6 54.bxa6 bxa6
 29/46+	00:34	 91,693k	2,661k	+3.27	38.b4 Kg7 39.c4 Kf6 40.Ke4 Ke7 41.c5 gxh5 42.gxh5 Ke6 43.b5 a5 44.a4 f5+ 45.Kf4 Kd5 46.Kxf5 Kxc5 47.Kg6 Kb4 48.Kxh6 Kxa4 49.Kg6 Kxb5 50.h6 a4 51.h7 Kc4 52.h8Q
 29/56	00:47	 123,991k	2,633k	+3.51	38.b4 Kg7 39.c4 f5 40.c5 gxh5 41.gxh5 Kf6 42.Ke3 Ke5 43.Kf3 a6 44.Ke3 Kd5 45.Kf4 Kc4 46.Kxf5 Kxb4 47.Kg6 Kxc5 48.Kxh6 Kb4 49.Kg6 Ka3 50.h6 Kxa2 51.h7 b5 52.h8Q b4 53.Qh2+ Ka3 54.Qg3+ b3 55.Qd6+ Kb2 56.Qxa6 Kb1 57.Qa4 b2 58.Kf5 Kc1 59.Qc4+ Kd2
 30/47-	00:48	 128,463k	2,633k	 0.00	38.b4 Kg7 39.c4 f5 40.c5 gxh5 41.gxh5 Kf6 42.Ke3 Ke5 43.Kf3 a6 44.Ke3 Kd5 45.Kf4 Kc4 46.Kxf5 Kxb4 47.Kg6 Kxc5 48.Kxh6 Kb4 49.Kg6 Ka3 50.h6 Kxa2 51.h7 b5 52.h8Q b4 53.Qh2+ Ka3 54.Qg3+ b3 55.Qd6+ Kb2 56.Qxa6 Kb1 57.Qa4 b2 58.Kf5 Kc1 59.Qc4+ Kd2

[BeyondCritics]

I did not say, that this position should be evaluated as a win. I just suggested to consider king position in the eval, which in my opinion is not really done. It is impossible to discuss, if you just read into what i have written what you desire.

Furthermore i think it is not completely far fetched to try to evaluate such a position statically as win. The idea is, to alert the engine about a pending terrible danger, so that the engine does not go into such a mess without seeing a cure. Such techniques had been employed in the past, to avoid the engine getting trapped with its knight on a8 for example.

[Maxwell86]

Thank you all for your feedback!

Funny anecdote about this position: During the game, I rejected 35....Qxf3, because I thought the pawn ending is lost. However, when I was annotating this game, I blindly believed the evaluation of the engine (after 10 seconds) and wrote "35....Qg2+? better was 35....Qxf3 with equality". When I showed the game to GM Mikhail Gurevich, together with my annotations, he discovered the mistake in my analysis...

After 7 years, I'm surprised to see that the current engines still have some difficulties with the position and that they need some time to understand it.

[zullil]

or maybe stockfish simply cannot find the win in a pawn endgame.
Did not check if b4 is the only winning move

[d]8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38 bm b4

Latest asmFish can find b4, so surely Stockfish will too.

Code: Select all

info depth 43 seldepth 50 multipv 1 time 30982 nps 70710489 score cp 0 nodes 2190752398 tbhits 0 hashfull 145 pv d3e3 f7f5 e3f4 f5g4 f4g4 h7g7 a2a4 g6h5 g4h5 a7a5 c2c3 g7f6 b2b4 a5b4 c3b4 f6e5 a4a5 e5d5 b4b5 d5c5 a5a6 b7a6 b5a6 c5b6 a6a7 b6a7 h5g6 h6h5 g6g5 a7b6 g5f4 b6a6 f4f3 a6b5 f3f4 b5a6
info depth 44 currmove d3e3 currmovenumber 1
info depth 44 currmove h5g6 currmovenumber 2
info depth 44 currmove d3e4 currmovenumber 3
info depth 44 currmove c2c4 currmovenumber 4
info depth 44 currmove a2a4 currmovenumber 5
info depth 44 currmove b2b4 currmovenumber 6
info depth 44 seldepth 50 multipv 1 time 59142 nps 71668168 score cp 7 lowerbound nodes 4238598822 tbhits 0 hashfull 308 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 62530 nps 71477333 score cp 14 lowerbound nodes 4469477655 tbhits 0 hashfull 331 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 64836 nps 71393852 score cp 25 lowerbound nodes 4628891838 tbhits 0 hashfull 346 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 66376 nps 71438851 score cp 40 lowerbound nodes 4741825215 tbhits 0 hashfull 354 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 68620 nps 71377407 score cp 61 lowerbound nodes 4897917682 tbhits 0 hashfull 365 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 70602 nps 71446546 score cp 89 lowerbound nodes 5044269079 tbhits 0 hashfull 371 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 72766 nps 71449291 score cp 127 lowerbound nodes 5199079180 tbhits 0 hashfull 377 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 75108 nps 71481010 score cp 175 lowerbound nodes 5368795754 tbhits 0 hashfull 390 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 77706 nps 71726407 score cp 237 lowerbound nodes 5573572243 tbhits 0 hashfull 394 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 82051 nps 71931424 score cp 317 lowerbound nodes 5902045348 tbhits 0 hashfull 406 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 88173 nps 72685179 score cp 419 lowerbound nodes 6408870344 tbhits 0 hashfull 426 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 97930 nps 74597062 score cp 548 lowerbound nodes 7305290352 tbhits 0 hashfull 460 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 108381 nps 75959788 score cp 711 lowerbound nodes 8232597850 tbhits 0 hashfull 484 pv b2b4
info depth 44 currmove b2b4 currmovenumber 1
info depth 44 seldepth 60 multipv 1 time 135651 nps 79064144 score cp 917 lowerbound nodes 10725130221 tbhits 0 hashfull 558 pv b2b4

And returns a mate score eventually:

Code: Select all

info depth 45 seldepth 86 multipv 1 time 1658829 nps 84725270 score mate 31 nodes 140544735113 tbhits 0 hashfull 999 pv b2b4 h7g7 c2c4 g7f6 d3e4 f6e6 c4c5 a7a6 a2a4 e6e7 e4e5 f7f6 e5d5 g6h5 g4h5 e7f7 d5e4 f7e6 a4a5 e6d7 e4f5 d7e7 f5g6 f6f5 g6f5 e7d7 f5g6 d7c6 g6h6 c6b5 h6g5 b5b4 h5h6 b4a5 h6h7 a5b4 h7h8q a6a5 h8d4 b4b5 d4c3 a5a4 g5f5 a4a3 c3a3 b7b6 c5c6 b5c6 f5e6 c6b5 a3b3 b5c6 b3c3 c6b7 e6d7 b7a7

[Rodolfo Leoni]

Thank you all for your feedback!

Funny anecdote about this position: When I was annotating this game, I blindly believed the evaluation of the engine (after 10 seconds) and wrote "35....Qg2+? better was 35....Qxf3 with equality". When I showed the game to GM Mikhail Gurevich, together with my annotations, he discovered the mistake in my analysis...

After 7 years, I'm surprised to see that the current engines still have some difficulties with the position and that they need some time to understand it.

It'd be very nice if you share with us some other positions and... anecdotes!

[peter]

Did not check if b4 is the only winning move

[d]8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38 bm b4

Seems so too, Uri.
BTW, in 2MV- mode it took SF about a minute to "see" b4, but much longer, to get it into output (it was in "computing-now" of the GUI as number 1 for about 5 minutes). Obviously difficult for the engine to solve the fail high again. Was in depth 44 already still stuck, start- stop brought up this in depth 27 then at once, so it was in hash for a long time before restarting the analysis- mode.
No tbs used:

624: Michiels,B - Blass,U, CCC
8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 1

Analysis by Stockfish 140717 64 POPCNT:

1. +- (15.02): 39.b4 Kg7 40.c4 a6 41.a4 Kf6 42.Ke3 Ke7 43.c5 Kf8 44.Kd3 Ke8 45.Ke4 Kf8 46.Kd4 Ke7 47.g5 hxg5 48.h6 Kf8 49.b5 Kg8 50.c6 bxc6 51.bxc6 Kh7 52.Ke5 Kxh6 53.c7 Kh5 54.c8Q f5 55.Qxa6

2. = (0.00): 39.Ke3 f5 40.Kf4 fxg4 41.Kxg4 a5 42.a4 gxh5+ 43.Kxh5 Kg7 44.c3 Kf6 45.b4 Ke5 46.bxa5 Ke4 47.Kxh6 Kd3 48.Kg5 Kxc3 49.a6 bxa6 50.a5 Kc4 51.Kf5 Kb4 52.Kf4 Kxa5 53.Ke3 Kb4 54.Kd2 Kb3 55.Kc1 a5

Jörg Oster, where's your new patch for this position?


BTW, komodo 11.2 gets it almost at once (10" at 24 threads without tbs in single variant mode)

[peter]

Did not check if b4 is the only winning move

[d]8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 38 bm b4

Seems so too, Uri.

Oops:

At least 39.a4 works too.

Here with full Syzygys, after having been "shown" b4 and then computing "next best move":


8/pp3p1k/6pp/7P/6P1/3K4/PPP5/8 w - - 0 1

Analysis by Stockfish MateFinder 64:

39.b4
+- (8.42 ++) Depth: 27/33 253MN, tb=2234809

...
Fritz-GUI y
...

39.a4 f5 40.a5 fxg4 41.c4 gxh5 42.c5 a6 43.b4 h4 44.Ke3 Kg6 45.b5 axb5 46.a6 h3 47.Kf2 bxa6 48.c6 h2 49.Kg2 Kf6 50.c7 Ke6 51.c8Q+ Kd5 52.Qxa6 Kc4 53.Qxh6 Kb4 54.Qxh2 Ka5 55.Qf4 Kb6 56.Qxg4 Ka5 57.Qg3
+- (9.83) Depth: 34/49 00:05:12 10540MN, tb=287950846

[Lyudmil Tsvetkov]

The following position occured in the game Dominguez Perez - Michiels (2010):

[d]6k1/1p3pp1/p6p/7P/3Q2P1/5P2/PPPK4/5q2 b - - 2 35

For humans it is intuitively clear that the pawn ending after 35....Qxf3 36.Qd8+ Kh7 37.Qd3+ should be winning for white: a centralized king and a pawn majority at the queen side.
However, Stockfish 8 thinks 35....Qxf3 is the best move for black, only at a high depth, it prefers 35....Qg2+.

After 35....Qxf3 36.Qd8+ Kh7 37.Qd3+ Qxd3, both recaptures win for white.

[d]8/1p3ppk/p6p/7P/6P1/3q4/PPPK4/8 w - - 0 38

Curiously, even in this position, Stockfish 8 needs a high depth to realize that 38.Kxd3 wins.

Just wanted to share this position!

so far I have not won a single pawn endgame from SF.

minor piece endgames, yes, more complicated positions, of course, frequently, but not a single pawn endgame.

my SF(which is of course buggy, as always ) shows around 100cps white advantage for this position, which I think is more than satisfactory score.

the position, although simple still requires some depth.

for example, 40 plies on, one of the positions hit is the following:

[d]8/8/K1k3pp/8/P5P1/8/1P6/8 b - - 0 18

simple to calculate from here, but 40 plies back, with all the available other branches too?

[Lyudmil Tsvetkov]

another very interesting question is whether there is any disticntion at all between Qf3 and Qg2?

because, with quick check with both SF and Komodo, both engines seem to win the simple pawn, as well as the queen endgame.

admittedly, leaving queens on board gives the much better chances to defend, but still, quite probably, the game is lost for black.

white has:
- a pawn more
- more active king
- nice advanced pawns in the form of h5 and g4

if you ask me, too many related eval advantages for black to save the game in any line.

but again, this is just a quick check on my part, to spur some thought.

was this post trollish, gosh, I see trolls all around?