check extension

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hgm
Posts: 27790
Joined: Fri Mar 10, 2006 10:06 am
Location: Amsterdam
Full name: H G Muller

Re: check extension

Post by hgm »

Yeah, I considered that, but I did not want to use promoted pieces (so also no Bishops on the same shade).
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lucasart
Posts: 3232
Joined: Mon May 31, 2010 1:29 pm
Full name: lucasart

Re: check extension

Post by lucasart »

hgm wrote: ↑Mon Dec 03, 2018 5:42 pm This is a pretty long sequence:
[pgn][Event "Edited game"] [Site "ONTWIKKELLAPTOP"] [Date "2018.12.03"] [Round "-"] [White "-"] [Black "-"] [Result "*"] [FEN "4n2q/Qp4r1/8/4k3/1N6/N1K5/5n2/3R4 w - - 0 1"] [SetUp "1"] 1. Qb8+ Rc7+ 2. Nc4+ Kf4+ 3. Rd4+ Ne4+ * [/pgn]
I am not sure if the requirement that SEE>=0 is realistic in such a sequence: the checks are also evasions, and pruning check evasions seems risky. Without this requirement you could probably make much loger sequences.
Nice one. Thanks.

Yes, the hope was that SEE >= 0 helps keep such sequences small and rare.
Theory and practice sometimes clash. And when that happens, theory loses. Every single time.
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MikeB
Posts: 4889
Joined: Thu Mar 09, 2006 6:34 am
Location: Pen Argyl, Pennsylvania

Re: check extension

Post by MikeB »

hgm wrote: ↑Mon Dec 03, 2018 5:42 pm This is a pretty long sequence:
[pgn][Event "Edited game"] [Site "ONTWIKKELLAPTOP"] [Date "2018.12.03"] [Round "-"] [White "-"] [Black "-"] [Result "*"] [FEN "4n2q/Qp4r1/8/4k3/1N6/N1K5/5n2/3R4 w - - 0 1"] [SetUp "1"] 1. Qb8+ Rc7+ 2. Nc4+ Kf4+ 3. Rd4+ Ne4+ * [/pgn]
I am not sure if the requirement that SEE>=0 is realistic in such a sequence: the checks are also evasions, and pruning check evasions seems risky. Without this requirement you could probably make much loger sequences.
Nice mate in 26
[d]4n2q/Qp4r1/8/4k3/1N6/N1K5/5n2/3R4 w - - 0 1

Code: Select all

dep	score	nodes	time	(not shown:  tbhits	knps	seldep)
 44	  #26 	1.33G	0:39.89	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8# 
 43	  #26 	767.4M	0:23.26	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 42	  #26 	663.0M	0:20.18	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 41	  #26 	485.9M	0:14.95	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 40	  #26 	451.5M	0:13.89	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 39	  #26 	417.6M	0:12.86	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 38	  #26 	386.6M	0:11.92	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Re5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 37	  #26 	303.9M	0:09.39	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Re5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 36	  #26 	291.6M	0:09.02	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Rb5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 35	  #26 	281.2M	0:08.69	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Re5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 34	  #26 	236.4M	0:07.28	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Re5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 33	  #26 	229.6M	0:07.07	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Re5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 32	  #26 	223.6M	0:06.88	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qd5+ Kh7 Qh1+ Rh6 Qxh6+ Kxh6 Nf7+ Kg7 Nxh8 Kxh8 Kd4 Kg7 Rf5 Kg6 Ke5 Kg7 Ke6 Kg6 Re5 Kg7 Rg5+ Kh6 Kf6 Kh7 Rh5+ Kg8 Rh3 Kf8 Rh8 
 31	  #35 	214.9M	0:06.61	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qd8 Nxf6 Rg3+ Kb2 Rg2 Qxg2 Qxf6 Qxb7+ Kg8 Qc8+ Kf7 Qd7+ Kg8 Qg4+ Kf8 Kc3 Kf7 Nd6+ Qxd6 Qf4+ Kg7 Rg5+ Qg6 Rxg6+ Kxg6 Kd4 Kg7 Qg5+ Kf8 Qf6+ Ke8 Qg6+ Kd7 Qb6 Kc8 Qb5 Kd8 
 30	  #31 	159.2M	0:04.86	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qd8 Nxf6 Kf8 Qc5+ Kf7 Nd6+ Kxf6 Rf5+ Ke6 Qd5+ Ke7 Qe5+ Kd7 Qxg7+ Qe7 Rf7 Qxf7 Qxf7+ Kxd6 Qxb7 Ke5 Qc6 Kf4 Kd4 Kf5 Qe4+ Kf6 Kd5 Kf7 Ke5 Ke7 Qb7+ Kf8 Qc8+ Kf7 
 29	  #64 	136.6M	0:04.17	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Kg8 Qg2+ Qg7 Qxg7+ Kxg7 Ne8+ Kf7 Nxf6 Kf8 Nd5 Kg7 Nb6 Kh8 Re7 Kg8 Nc4 Kf8 Re3 Kg8 Re5 
 28	+58.79 	60.5M  	0:01.99	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qd8 Nxf6 Kf8 Qc5+ Kf7 Nd6+ Kxf6 Rf5+ Ke6 Qd5+ Ke7 Qe5+ Kd7 Qxg7+ Kxd6 Qd4+ Ke6 Re5+ Kf6 Qxd8+ Kxe5 Qe7+ Kf5 Qxb7 Kg6 Qc6+ Kf5 Qd5+ Kf4 Kd4 Kg3 Qa8 Kg4 Qg2+ Kf4 
 27	+56.39 	45.9M  	0:01.58	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qd8 Nxf6 Rg3+ Kb2 Rg2 Qxg2 Qxf6 Qxb7+ Kg8 Kb3 Kf8 Qb4+ Kg8 Re8+ Kg7 Qe7+ Qxe7 Rxe7+ Kf6 Re3 Kg5 Kc3 
 26	+53.14 	37.1M  	0:01.32	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qh3+ Rh6 Qf5+ Rg6 Qh5+ Rh6 Qxh6+ Kxh6 Nf7+ Kh7 Nxh8 Kxh8 Rb5 Kg7 Rxb7+ Kg6 Rb5 Kf6 Kc3 Kg7 Kd4 Kf6 Re5 
 25	+53.05 	35.3M  	0:01.26	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Qg7 Qxg7+ Kxg7 Ne8+ Kf7 Nxf6 Kxf6 Rb5 Ke6 Kc3 Kd6 Kd4 Ke6 Rd5 Kf6 Kc3 Kf7 Rb5 Kg8 Kd4 Kh7 Ke5 
 24	+53.05 	32.1M  	0:01.17	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Qg7 Qxg7+ Kxg7 Ne8+ Kf7 Nxf6 Kxf6 Rb5 Ke6 Kc3 Kd6 Kd4 Ke6 Rd5 Kf6 Kc3 
 23	+52.86 	19.3M  	0:00.67	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Rg6 Nd6+ Kg7 Nxf6 Rxf6 Qg2+ Kh7 Qxb7+ Qg7 Qxg7+ Kxg7 Ne8+ Kf7 Nxf6 Kxf6 Rb5 Kf7 Kc3 Ke6 Kd4 Kf6 Rh5 Ke6 Re5+ Kd6 
 22	+19.75 	13.5M  	0:00.45	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Qh4 Nd6+ Kg6 Qc2+ Ne4 Rxe4 Qxe4 Qxe4+ Kh5 Nf5 Rg1 Qh4+ Kg6 Nfe7+ Kg7 Qd4+ Kh7 Qxg1 
 21	+17.82 	10.3M  	0:00.34	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qd8 Nxf6 Rg6 Nd6+ Qxd6 Ne4+ Qf6 Nxf6 Rxf6 Rf5 Ke7 Rxf6 Kd8 Kb2 Kd7 
 20	+13.43 	5.92M  	0:00.20	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Rg6 Nd6+ Kg8 Ne7+ Kg7 Nxg6 Qh1 Re7+ Kg8 Qxf6 Qg2+ Kb1 Qh1+ Kc2 Qg2+ Kc1 
 19	+13.06 	5.30M  	0:00.18	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg8 Ne7+ Kh7 Nxg6 Qg7 Qh4+ Kg8 Ne7+ Kf8 Nef5 Nd5+ Kd4 
 18	+12.80 	5.18M  	0:00.18	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg8 Ne7+ Kh7 Nxg6 Qg7 Qh4+ Kg8 Ne7+ Kf8 Nef5 Nd5+ Kd4 
 17	+12.26 	4.18M  	0:00.14	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 Nxf6 Qh1 Re7+ Kh8 Nf7+ Kg7 Ng5+ Kh6 Rh7+ Kxg5 Rxh1 Rxf6 Qg2+ Kf5 Qxb7 
 16	+11.81 	3.92M  	0:00.14	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qd8 Nxf6 Kf8 Re8+ Qxe8 Nxe8+ Kxe8 Ne5 Re7 Qf6 Rxe5 Qxe5+ Kd7 Kb4 
 15	+10.79 	3.43M  	0:00.12	Nc4+ Ke6 Re1+ Kf7 Qxb7+ Kf6 Qf3+ Kg5 Qg2+ Ng4 Re5+ Kh4 Qh1+ Kg3 Qxh8 Nxe5 Nxe5 
 14	+10.41 	3.11M  	0:00.11	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Qh3+ Kb4 Rg6 Nd6+ Kg8 Nxf6+ Rxf6 
 13	+9.89 	3.08M  	0:00.11	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 Qd8 Nxf6 
 12	+9.75 	3.00M  	0:00.11	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg8 Ne7+ Kh7 
 11	+9.37 	2.01M  	0:00.07	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg3+ Kb2 
 10	+9.13 	1.52M  	0:00.05	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf5 Re5+ Kg6 Qg1+ Kf7 Qf2+ Nf6 Nd5 Rg6 Nd6+ Kg7 
  9	+9.91 	531745	0:00.02	Nc4+ Ke6 Re1+ Kf7 Qxb7+ Kf6 Qf3+ Kg5 
  8	+7.90 	102067	0:00.01	Nc4+ Kf5 Qxf2+ Ke6 Qe3+ Kf7 Re1 Nd6 Nxd6+ Kg6 Qe4+ Kf6 Kb3 
  7	+10.28 	71770  	0:00.00	Nc4+ Ke6 Re1+ Ne4+ Rxe4+ Kf7 Qxb7+ Kg6 Rg4+ Kh5 
  6	+8.07 	38438  	0:00.00	Nc4+ Kf5 Qxf2+ Kg6 Qe3 Rc7+ Kb3 Kf7 
  5	+8.69 	18329  	0:00.00	Qxf2 Rc7+ Nc4+ Ke6+ Kb3 Qh3+ Rd3 
  4	+5.20 	16380  	0:00.00	Qxf2 Ke6 Kc2 Rc7+ Kb1 
  3	+5.78 	13308  	0:00.00	Qxf2 Ke6 Kc2 
  2	+8.18 	9174    	0:00.00	Qxf2 Ke6 
  1	+10.48 	5185    	0:00.00	Qxf2 Qh3+ Kb2 
  1	Found 1511 tablebases 
  0	#
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