Start Your Engines

[MikeB]

"All moves win except the rook capture. Kg2 is mate in 32."

Yes, but Kg2, Kg1 and Kh2 are mate in 35

Engine: ChestUCI Ver.5.2
von Franz Huber

35.02 0:50 +M35 1.Kg1 1523

35.03 0:50 +M35 1.Kh2 1523

35.04 0:50 +M35 1.Kg2 1523

35/35 0:50 +M35 1.Kg2 Tg7 2.Kf2 Thh7 3.Ke2 Th6 4.Ke3 Thh7
5.Kd4 Th6 6.Kc5 Thh7 7.Kb6 Th6
8.Kxa6 Thh7 9.Kxa5 Th6 10.Kxa4 Thh7
11.Kxa3 Th6 12.Ka4 Thh7 13.Ka5 Th6
14.a4 1529

Interesting. I think Cfish also ended up with mate-in-34. Will need to check again.

I also ended up with mate-in-34 using SF-McB

[Rebel]

Ed, you have a PM

Sorry friend, I can't answer before next thursday

[MikeB]

[d] 4b1kn/3p1p1r/p2P1Ppr/p5Pp/p6P/p7/P7/7K w - -
Forgot to ask, is there any engine that produces a winning score from the start position? Just curious.

the very latest dev-SF-McB (not released) is now getting a winning score with a clean start...
18 threads 8MB hash

Code: Select all

dep	score	nodes	time	(not shown:  tbhits	knps	seldep)
 84	+132.23!	66.1G	28:45.50	Kg2! 
 84	+65.44!	66.1G	28:45.48	Kg2! 
 84	+30.86!	66.1G	28:45.47	Kg2! 
 84	+28.26!	66.1G	28:45.43	Kg2! 
 84	+26.42!	65.0G	28:13.94	Kg2! 
 84	+23.61!	61.1G	26:33.13	Kg2! 
 84	+23.61!	61.1G	26:33.13	Kg2! 
 84	+21.77!	59.9G	25:54.23	Kg2! 
 84	+19.92!	58.0G	25:01.67	Kg2! 
 83	+18.08!	56.2G	24:08.98	Kg2! 
 83	+17.02!	55.3G	23:43.34	Kg2! 
 83	+16.00!	53.4G	22:53.31	Kg2! 
 83	+14.98!	52.8G	22:36.40	Kg2! 
 83	+13.96!	52.3G	22:25.24	Kg2! 
 83	+12.94!	50.5G	21:40.08	Kg2! 
 83	+11.92!	48.8G	20:47.83	Kg2! 
 83	+10.90!	47.6G	20:18.41	Kg2! 
 82	+9.88!	42.0G	18:02.91	Kg2! 
 82	+9.28!	40.3G	17:16.34	Kg2! 
 82	+8.68!	35.9G	15:33.48	Kg2! 
 82	+8.08!	31.7G	13:57.59	Kg2! 
 82	+7.48!	31.7G	13:57.58	Kg2! 
 82	+6.88!	28.3G	12:42.94	Kg2! 
 82	+6.28!	27.7G	12:26.51	Kg2! 
 81	+5.68!	24.9G	11:31.24	Kg2! 
 81	+5.30!	22.8G	10:37.50	Kg2! 
 81	+4.93!	21.3G	9:58.43	Kg2! 
 81	+4.55!	20.0G	9:23.99	Kg2! 
 81	+4.18!	19.1G	9:00.56	Kg2! 
 81	+3.80!	18.7G	8:50.73	Kg2! 
 80	+3.43!	18.5G	8:44.62	Kg2! 
 80	+3.18!	17.0G	8:10.96	Kg2! 
 80	+2.93!	16.1G	7:50.72	Kg2! 
 80	+2.68!	15.9G	7:44.26	Kg2! 
 80	+2.43!	15.5G	7:33.26	Kg2! 
 79	+2.18!	13.9G	7:00.07	Kg2! 
 79	+2.00!	11.6G	6:14.26	Kg2! 
 79	+1.82!	11.3G	6:08.00	Kg2! 
 79	+1.64!	11.3G	6:07.84	Kg2! 
 78	+1.46!	8.32G	4:49.92	Kg2! 
 78	+1.32!	7.91G	4:37.01	Kg2! 
 78	+1.18!	7.91G	4:36.97	Kg2! 
 77	+1.05!	5.26G	3:14.43	Kg2! 
 77	+0.93!	4.39G	2:44.34	Kg2! 
 76	+0.82!	3.23G	2:00.20	Kg2! 
 76	+0.75!	2.44G	1:29.59	Kg2! 
 76	+0.67!	2.01G	1:14.53	Kg2! 
 76	+0.60!	1.94G	1:11.61	Kg2! 
 76	+0.52!	1.79G	1:06.01	Kg2! 
 76	+0.45!	1.67G	1:01.91	Kg2! 
 76	+0.37!	1.61G	0:59.51	Kg2! 
 76	+0.30!	1.49G	0:55.24	Kg2! 
 76	+0.22!	1.32G	0:48.97	Kg2! 
 76	+0.15!	1.16G	0:42.82	Kg2! 
 76	+0.07!	887.1M	0:32.52	Kg2! 
 75	  0.00 	419.8M	0:14.56	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 74	  0.00 	342.7M	0:11.71	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 73	  0.00 	155.1M	0:04.94	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 72	  0.00 	121.2M	0:03.84	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 71	  0.00 	118.6M	0:03.75	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 70	  0.00 	117.3M	0:03.71	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 69	  0.00 	115.9M	0:03.67	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 68	  0.00 	111.5M	0:03.52	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 67	  0.00 	111.4M	0:03.51	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 66	  0.00 	55.4M  	0:01.68	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 65	  0.00 	46.2M  	0:01.38	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 64	  0.00 	28.5M  	0:00.82	Kg2 Rg7 Kg3 Kh7 Kf3 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 63	  0.00 	21.1M  	0:00.60	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 62	  0.00 	17.6M  	0:00.49	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 61	  0.00 	15.9M  	0:00.44	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 60	  0.00 	15.1M  	0:00.42	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 59	  0.00 	14.4M  	0:00.40	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 58	  0.00 	12.4M  	0:00.34	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 57	  0.00 	11.7M  	0:00.32	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 56	  0.00 	8.23M  	0:00.22	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 55	  0.00 	7.97M  	0:00.21	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 54	  0.00 	6.29M  	0:00.16	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 53	  0.00 	5.93M  	0:00.16	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 52	  0.00 	5.29M  	0:00.14	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 51	  0.00 	4.86M  	0:00.13	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 50	  0.00 	4.17M  	0:00.11	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 49	  0.00 	3.70M  	0:00.10	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 48	  0.00 	3.52M  	0:00.09	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kd5 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 47	  0.00 	3.04M  	0:00.08	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 46	  0.00 	2.91M  	0:00.08	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 45	  0.00 	2.64M  	0:00.07	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 44	  0.00 	2.27M  	0:00.06	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 43	  0.00 	2.10M  	0:00.06	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 42	  0.00 	1.85M  	0:00.05	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 41	  0.00 	1.69M  	0:00.04	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 40	  0.00 	1.53M  	0:00.04	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 39	  0.00 	1.42M  	0:00.04	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 38	  0.00 	1.28M  	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 37	  0.00 	1.27M  	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kd5 Rg7 Kc5 Kh7 Kd4 Kg8 Kc5 
 36	  0.00 	1.20M  	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kd5 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 35	  0.00 	1.11M  	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 34	  0.00 	1.05M  	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 33	  0.00 	987757	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 32	  0.00 	963662	0:00.03	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 31	  0.00 	808385	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 30	  0.00 	775657	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 29	  0.00 	746816	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 28	  0.00 	708787	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 27	  0.00 	693673	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 26	  0.00 	667036	0:00.02	Kg2 Rg7 Kf3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 25	  0.00 	629728	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 24	  0.00 	618647	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 23	  0.00 	614610	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 22	  0.00 	610600	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 21	  0.00 	606601	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 20	  0.00 	602805	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 19	  0.00 	599002	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 18	  0.00 	595580	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 17	  0.00 	591456	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 Kc5 Kh7 Kb6 Rfg8 Kc5 Rf8 
 16	 -12.45 	512945	0:00.02	Kg2 Rg7 Kg3 Kh7 Kf4 Rg8 Ke4 Rf8 Kd5 Kg8 Kc5 Rh7 Kb6 Rg7 Kxa6 Rh7 Kb5 Rh6 Kxa4 
 15	 -14.11 	340067	0:00.01	Kg2 Rg7 Kf3 Kh7 Kf4 Rg8 Ke5 Rf8 Kd4 Kg8 Kc5 Rh7 Kb6 Rg7 fxg7 Kxg7 Kxa6 f5 Kxa5 Nf7 
 14	 -13.20 	266387	0:00.01	Kg2 Rg7 Kg3 Kh7 fxg7 Kxg7 gxh6+ Kxh6 Kf4 f6 Ke4 Bf7 Ke3 Bxa2 Kd3 Nf7 Ke3 Nxd6 
 13	 -13.32!	252578	0:00.01	Kg2! 
 12	 -12.89 	131445	0:00.00	Kg2 Rg7 fxg7 Rh7 gxh8=R+ Rxh8 Kf3 Kg7 Kf4 f5 gxf6+ Kxf6 Kf3 Bf7 Kg3 Bxa2 Kf4 Bd5 
 11	 -12.75 	101276	0:00.00	Kg2 Rg7 fxg7 Rh7 gxh8=Q+ Rxh8 Kf3 Kg7 Kf4 f6 gxf6+ Kxf6 Kg3 Bf7 Kg2 Bxa2 
 10	 -12.09!	48633  	0:00.00	Kg2! 
  9	 -14.20 	16642  	0:00.00	Kg2 Kf8 gxh6 Rxh6 Kg3 g5 hxg5 h4+ Kh3 Rh5 Kg4 
  8	 -14.14!	12934  	0:00.00	Kg2! 
  7	 -14.42 	10002  	0:00.00	Kg2 Kf8 gxh6 Rxh6 Kf3 Kg8 Kf2 Rh7 
  6	 -12.88!	6239    	0:00.00	Kg2! 
  5	 -14.12!	3698    	0:00.00	gxh6! 
  4	 -14.65 	2613    	0:00.00	gxh6 Rxh6 Kg2 Kf8 Kg3 
  3	 -13.97 	1693    	0:00.00	gxh6 Rxh6 Kh2 Rh7 
  2	  0.00 	1024    	0:00.00	gxh6 Rxh6 Kg1 
  1	 -15.72 	390      	0:00.00	gxh6 Rxh6 

Will let it run for a few more minutes to see if a mate score pops up, it looks like it might be getting close

SF 9 will be released within few days, so the next release of SF-McB will be delayed a proper amount of time out of respect for the SF authors and the scores of contributors, both those that submit patches and hardware time. SF-9 will be an awesome release and SF-McB only exists because of SF.

...here's to Stockfish -9 👊👍

[Rebel]

Week-3 up, one day too early, but it suits me better.

Regarding the mate in x position, it's (IMO) best to start from move 20. Kd8 after eating all the pawns, the queen promotion and then move the king to d8 since his majesty needs to be there for the mate sequence.

Then let engines think for the shortest mate.

[d]Q2Kbrkn/3p1p2/3P1Ppr/6Pp/7P/8/8/8 b - -
To be absolutely sure move the positions of the black king and black rooks to different squares and search again, there are only a few combinations. And to me the correct answer is 34.

Example.

[pgn][Event "Composition"]
[Site "White to move and mate"]
[Date "19/7/2009"]
[White "?"]
[Black "?"]
[Result "1-0"]
[FEN "4b1kn/3p1p1r/p2P1Ppr/p5Pp/p6P/p7/P7/7K w - -"]

1. Kg2 Rg7 2. Kf3 Kh7 3. Ke4 Rg8 4. Kd5 Rf8 5. Kc5 Kg8 6. Kb6 Rh7 7. Kxa6 Rh6 8. Kxa5 Kh7
9. Kxa4 Rg8 10. Kxa3 Rg7 11. Kb4 Kg8 12. a4 Kh7 13. a5 Rg8 14. a6 Rf8 15. a7 Rg8 16. a8Q
Rf8 17. Kb5 Kg8 18. Kb6 Rh7 19. Kc7 Rh6 20. Kd8 Rh7 21. Qe4 Rg7 22. Qf4 Rh7 23. Qe5 Rh6
24. Qxe8 Rxe8+ 25. Kxe8 Rh7 26. Kxd7 Rh6 27. Ke8 Rh7 28. d7 Rg7 29. d8Q Kh7 30. fxg7
Kxg7 31. Ke7 f6 32. Qf8+ Kh7 33. gxf6 g5 34. Qg7# 1-0[/pgn]

[Ovyron]

And to me the correct answer is 34.

Yes, I actually went and highly interacted with the positions trying all useful conbinations by black to try to delay mate and for white to speed up the mate. Interestingly, there were some tricks by black that allowed to delay mate if white tried the "King to c8"+"Queen to e4" plan, forcing white to play "Qe5!" and go for "fxg7" eating a rook there and mate differently, but trying to put Qe5 ASAP there to save time allowed a different set up that was drawn after "Qxe8".

So no matter what, in the best defenses White might have to do some careful dancing to mate in 34.

I even wonder if after what I've seen, I could savage a draw or at least be mated in more than 34 against an opponent that only knows the principles of the mate, but not these tricks and intrincacies, I was shook with the engine showing a sudden 0.00 and telling me "Haha! You fool! You just allow a rook escape if you play like that! Your queen has to dance a bit on the e file if I play this!"

For real the funniest position of the last week, considering I started with a mate in 40 or something and had to shave it until I was certain a mate in 33 wasn't possible, but at some point I thought I was close!

[Vinvin]

Week-3 up, one day too early, but it suits me better.

I found 3 solutions in 1 second from memory
But I'll try some engines to find the fastest one

[Scally]

Similar here,

But it took me far less than 5 days this time ...


Cheers,

Al (aka Scally)

[Uri Blass]

I think that it may be interesting to see results of different engines in this competition.

Note that stockfish9 can solve one of the positions in week 3 very fast.

[Vinvin]

I think that it may be interesting to see results of different engines in this competition.

I planned to do that after the next challenge (for the 12 first positions).

[Ovyron]

Note that stockfish9 can solve one of the positions in week 3 very fast.

As does Houdini and Komodo. And Fritz 15...

I actually had to dig up some old engine that doesn't get it.

Position 4, on the other hand, has me stumped, I may fail another one - though, I'll be sincere, I expected all 4 positions of all weeks to be as hard as this one.