Test position

[Arpad Rusz]

The following diagram helps to understand the solution:



There are a set of King/Rook(!) corresponding squares on the board.

[Arpad Rusz]

Probably you all know this elementary position:

[D]8/2k5/p1P5/P1K5/8/8/8/8 w - - 0 1
White wins

Actually White wins in a similar way like in the first endgame.

[peter]

The following diagram helps to understand the solution:



There are a set of King/Rook(!) corresponding squares on the board.

Very well, Arpad!
Then there are just two little more sophistications, first of course not to fall into 3 fold trap and then not to move white King to d2 when black rook is on g4, cause it could take pawn d4 at this very moment, the c-pawn tied to its king by the black bishop.
Still I find it most amusing, that there isn't a single one and only very best move, not at first move for White and for Black or for White further on.
Of course there are single best moves for White still at every step, but "mistakes" as for second best ones usually can be corrected by a single move more.

1.Kf3?! is only one move longer to mate than 1.Ke3! and even if I said, who cares, that's the little but counting difference:

[Event "Studie"]
[Site "CCC"]
[Date "2012.03.07"]
[Round "30"]
[White "Bláthy"]
[Black "Rusz"]
[Result "1-0"]
[Annotator "Martan,Peter"]
[SetUp "1"]
[FEN "N3k1nR/p1p1Pp2/2P1pPr1/b2pP3/P1pP1K2/2P3p1/6P1/8 w - - 0 1"]
[PlyCount "59"]
[EventDate "2012.??.??"]

1. Ke3 (1. Kf3 Rg5 2. Ke2 Rg6 3. Kd2 Rg5 4. Kc2 Rg6 5. Kc1 Rg4 6. Kd1 Rg5 7.
Kd2 Rg6 8. Ke2 Rg4 9. Ke3 Rg5 10. Kf3 Rg6 11. Kf4 a6 12. Kf3 Rg5 13. Ke2 Rg6
14. Kd1 Rg4 15. Kc1 Rg6 16. Kc2 Rg4 17. Kd1 Rg5 18. Kd2 Rg6 19. Ke2 Rg4 20. Ke3
Rg5 21. Kf3 Rg6 22. Kf4 Bb6 23. Nxb6 a5 24. Kf3 cxb6 25. Kf4 b5 26. axb5 a4 27.
b6 a3 28. b7 Rxf6+ 29. exf6 e5+ 30. dxe5 a2 31. b8=Q#) 1... Rg4 2. Ke2 Rg6 3.
Kd2 Rg5 4. Kc2 Rg4 5. Kd1 Rg5 6. Kd2 Rg6 7. Ke2 Rg4 8. Ke3 Rg5 9. Kf3 Rg6 10.
Kf4 a6 11. Kf3 Rg5 12. Ke2 Rg6 13. Kd1 Rg4 14. Kc1 Rg6 15. Kc2 Rg4 16. Kd1 Rg5
17. Kd2 Rg6 18. Ke2 Rg4 19. Ke3 Rg5 20. Kf3 Rg6 21. Kf4 Bb6 22. Nxb6 a5 23. Kf3
cxb6 24. Kf4 b5 25. axb5 a4 26. b6 a3 27. b7 Rxf6+ 28. exf6 e5+ 29. dxe5 a2 30.
b8=Q# 1-0

Btw the position is in Chest's database too.
Besides Komodo with nullmove off, Houdini is a great help here too, especially with persistent hash, learning file and mate search on.

[Arpad Rusz]

I know another study featuring King/Rook corresponding squares (T.Kok, 1938), but this is based on the Bláthy study:

[D]6kB/3Pp1Pp/1p1rP3/pP6/P1K5/P2p3p/3P3P/8 w - - 0 1
White wins

[peter]

I know another study featuring King/Rook corresponding squares (T.Kok, 1938), but this is based on the Bláthy study:

[D]6kB/3Pp1Pp/1p1rP3/pP6/P1K5/P2p3p/3P3P/8 w - - 0 1
White wins

Even harder because of the longer way with h-pawn and black King escaping, in Bláthy#s there was a single square for the black King only.

Started again with Komodo with nullmove off, took over with Houdini and his mate search on then.

6kB/3Pp1Pp/1p1rP3/pP6/P1K5/P2p3p/3P3P/8 w - - 0 1

Analysis by Houdini 2.0c Pro x64:

1. Kb3 Rd4 2. Kb2 Rd6 3. Ka1 Rd4 4. Kb1 Rd5 5. Ka2 Rd6 6. Kb2 Rd4 7. Kb3 Rd5 8. Kc3 Rd6 9. Kc4 h6 10. Kc3 Rd5 11. Kb2 Rd6 12. Kb1
+- (#45) Tiefe: 52/79 00:03:00 3770mN

Number of distance to mate should be rather exact, I guess.

[MOBMAT]

The following diagram helps to understand the solution:



There are a set of King/Rook(!) corresponding squares on the board.

Very well, Arpad!
Then there are just two little more sophistications, first of course not to fall into 3 fold trap and then not to move white King to d2 when black rook is on g4, cause it could take pawn d4 at this very moment, the c-pawn tied to its king by the black bishop.
Still I find it most amusing, that there isn't a single one and only very best move, not at first move for White and for Black or for White further on.
Of course there are single best moves for White still at every step, but "mistakes" as for second best ones usually can be corrected by a single move more.

1.Kf3?! is only one move longer to mate than 1.Ke3! and even if I said, who cares, that's the little but counting difference:

[Event "Studie"]
[Site "CCC"]
[Date "2012.03.07"]
[Round "30"]
[White "Bláthy"]
[Black "Rusz"]
[Result "1-0"]
[Annotator "Martan,Peter"]
[SetUp "1"]
[FEN "N3k1nR/p1p1Pp2/2P1pPr1/b2pP3/P1pP1K2/2P3p1/6P1/8 w - - 0 1"]
[PlyCount "59"]
[EventDate "2012.??.??"]

1. Ke3 (1. Kf3 Rg5 2. Ke2 Rg6 3. Kd2 Rg5 4. Kc2 Rg6 5. Kc1 Rg4 6. Kd1 Rg5 7.
Kd2 Rg6 8. Ke2 Rg4 9. Ke3 Rg5 10. Kf3 Rg6 11. Kf4 a6 12. Kf3 Rg5 13. Ke2 Rg6
14. Kd1 Rg4 15. Kc1 Rg6 16. Kc2 Rg4 17. Kd1 Rg5 18. Kd2 Rg6 19. Ke2 Rg4 20. Ke3
Rg5 21. Kf3 Rg6 22. Kf4 Bb6 23. Nxb6 a5 24. Kf3 cxb6 25. Kf4 b5 26. axb5 a4 27.
b6 a3 28. b7 Rxf6+ 29. exf6 e5+ 30. dxe5 a2 31. b8=Q#) 1... Rg4 2. Ke2 Rg6 3.
Kd2 Rg5 4. Kc2 Rg4 5. Kd1 Rg5 6. Kd2 Rg6 7. Ke2 Rg4 8. Ke3 Rg5 9. Kf3 Rg6 10.
Kf4 a6 11. Kf3 Rg5 12. Ke2 Rg6 13. Kd1 Rg4 14. Kc1 Rg6 15. Kc2 Rg4 16. Kd1 Rg5
17. Kd2 Rg6 18. Ke2 Rg4 19. Ke3 Rg5 20. Kf3 Rg6 21. Kf4 Bb6 22. Nxb6 a5 23. Kf3
cxb6 24. Kf4 b5 25. axb5 a4 26. b6 a3 27. b7 Rxf6+ 28. exf6 e5+ 29. dxe5 a2 30.
b8=Q# 1-0

Btw the position is in Chest's database too.
Besides Komodo with nullmove off, Houdini is a great help here too, especially with persistent hash, learning file and mate search on.

Update your records, this one is a dual.

Code: Select all

FEN: N3k1nR/p1p1Pp2/2P1pPr1/b2pP3/P1pP1K2/2P3p1/6P1/8 w - - 0 1

Crystal 080420:
 8	00:00	 44k	7,371k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 9	00:00	 69k	8,566k	-1.85	1.Nxc7+ Bxc7 2.Kf3 a6 3.Ke3 Bd8 4.Kf4 Bxe7 5.fxe7 Kxe7
 9	00:00	 69k	8,566k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 9	00:00	 69k	8,566k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 10	00:00	 182k	9,587k	-2.07	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.Kf3 a6 4.exd8Q+ Kxd8 5.Rh7 Nh6 6.Rg7 Kc7 7.Rxg6 fxg6 8.Kxg3 Kxc6 9.Kf3 Nf7
 10	00:00	 182k	9,587k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 10	00:00	 182k	9,587k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 11	00:00	 189k	9,475k	-1.92	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.Kf3 a6 4.exd8Q+ Kxd8 5.Rh7 Nh6 6.Rg7 Kc7 7.Kf4 Rxg7 8.fxg7 Kxc6 9.Kg5
 11	00:00	 189k	9,475k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 11	00:00	 189k	9,475k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 12	00:00	 382k	9,551k	-2.02	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8Q+ Kxd8 4.Kf4 Kc7 5.Rh7 Nh6 6.Rg7 Rxg7 7.fxg7 Kxc6 8.Kg5 Ng8 9.Kh4 Ne7 10.Kg4
 12	00:00	 382k	9,551k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 12	00:00	 382k	9,551k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 13	00:00	 493k	9,674k	-2.50	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8Q+ Kxd8 4.Kf3 a6 5.Kf4 Kc7 6.Rh7 Nh6 7.Rg7 Rxg7 8.fxg7 Kxc6 9.Kg5 Ng8 10.Kf4 Kd7 11.Kxg3 Ke7 12.Kf4
 13	00:00	 493k	9,674k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 13	00:00	 493k	9,674k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 14	00:00	 535k	9,723k	-2.50	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8Q+ Kxd8 4.Rh7 Nh6 5.Kf3 a6 6.Rg7 Rxg7 7.fxg7 Kc7 8.Kf4 Kxc6 9.Kg5 Ng8 10.Kg4 Kd7 11.Kxg3 Ke7 12.Kf4 f6 13.g4
 14	00:00	 535k	9,723k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 14	00:00	 535k	9,723k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 15	00:00	 821k	9,552k	-2.52	1.Nxc7+ Bxc7 2.Kf3 Bd8 3.exd8R+ Kxd8 4.Rh3 Nh6 5.Rxg3 Rxg3+ 6.Kxg3 Kc7 7.Kf4 Nf5 8.g4 Nh4 9.g5 Kxc6 10.Kg4 Ng6 11.Kh5 Kc7 12.Kh6
 15	00:00	 821k	9,552k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 15	00:00	 821k	9,552k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 16	00:00	 1,213k	9,626k	-2.61	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8Q+ Kxd8 4.Rh7 Nh6 5.Kf3 a6 6.Rg7 Kc7 7.Kf4 Rxg7 8.fxg7 Kxc6 9.Kg5 Ng8 10.Kg4 Kd7 11.Kxg3 Ke7 12.Kf3
 16	00:00	 1,213k	9,626k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 16	00:00	 1,213k	9,626k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 17	00:00	 1,946k	9,731k	-2.37	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8Q+ Kxd8 4.Kf4 Kc7 5.Rh3 Nxf6 6.exf6 Rxf6+ 7.Kg4 Kxc6 8.Rh8 Rf2 9.Ra8 Rxg2 10.Rxa7 Rg1 11.Rxf7
 17	00:00	 1,946k	9,731k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 17	00:00	 1,946k	9,731k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 18	00:00	 2,169k	9,727k	-2.10	1.Nxc7+ Bxc7 2.Kf3 a6 3.Ke3 Bd8 4.exd8R+ Kxd8 5.Rh3 Kc7 6.Kf4 Nxf6 7.exf6 Rxf6+ 8.Ke3 Kxc6 9.Rxg3 Kb6 10.Rg7 Ka5 11.g4 Kxa4 12.g5 Rf5 13.g6 fxg6 14.Rxg6 Kb3
 18	00:00	 2,169k	9,727k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 18	00:00	 2,169k	9,727k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 19	00:00	 3,974k	9,485k	-2.91	1.Nxc7+ Bxc7 2.Kf3 a6 3.Ke3 Bd8 4.exd8R+ Kxd8 5.Rh3 Kc7 6.Kf4 Nxf6 7.exf6 Kxc6 8.Rxg3 Rxf6+ 9.Ke3 Kb6 10.Rg7 Ka5 11.g4 Kxa4 12.g5 Rf1 13.Ke2 Rf5 14.g6 fxg6 15.Rxg6 Kb3
 19	00:00	 3,974k	9,485k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 19	00:00	 3,974k	9,485k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 20	00:00	 5,366k	9,515k	-2.35	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8Q+ Kxd8 4.Kf3 Kc7 5.Rh3 Nxf6 6.exf6 Rxf6+ 7.Kxg3 Kxc6 8.Rh1 Kb6 9.a5+ Kxa5 10.Ra1+ Kb6 11.Rb1+ Kc6 12.Ra1 Kb7 13.Rc1 a6 14.Rb1+ Ka7 15.Ra1 Rg6+ 16.Kf2 Kb6 17.Kf3
 20	00:00	 5,366k	9,515k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 20	00:00	 5,366k	9,515k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 21	00:01	 13,720k	9,877k	-2.71	1.Nxc7+ Bxc7 2.Ke3 a6 3.Kf3 Bb6 4.Kf4 Ba5 5.Kf3 Bc7 6.Ke3 Bd8 7.exd8R+ Kxd8 8.Kf4 Kc7 9.Rh3 Nxf6 10.exf6 Kxc6 11.Rxg3 Rxf6+ 12.Ke3 Kb6 13.Rg7 Ka5 14.g4 Kxa4 15.g5 Rg6 16.Rxf7 Kb3 17.Kd2 Rxg5 18.Rb7+ Ka3
 21	00:01	 13,720k	9,877k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 21	00:01	 13,720k	9,877k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 22	00:03	 31,659k	9,934k	-2.78	1.Nxc7+ Bxc7 2.Ke3 Bb6 3.Ke2 a6 4.Ke3 Bd8 5.exd8Q+ Kxd8 6.Kf4 Kc7 7.Rh3 Kxc6 8.Rxg3 Nxf6 9.exf6 Rxf6+ 10.Ke3 Kb6 11.Rg7 Ka5 12.g4 Kxa4 13.g5 Rg6 14.Rxf7 Kb3 15.Kd2 Rxg5 16.Rb7+ Ka3 17.Kc2 a5
 22	00:03	 31,659k	9,934k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 22	00:03	 31,659k	9,934k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 23	00:05	 54,935k	9,927k	-2.84	1.Nxc7+ Bxc7 2.Kf3 a6 3.Ke3 Bd8 4.exd8R+ Kxd8 5.Kf4 Kc7 6.Rh3 Nxf6 7.exf6 Kxc6 8.Rxg3 Rxf6+ 9.Ke3 Kb6 10.Rg7 Ka5 11.g4 Kxa4 12.g5 Rg6 13.Rxf7 Kb3 14.Rf6 Rxg5 15.Rxe6 Kxc3 16.Rxa6 Rg4
 23	00:05	 54,935k	9,927k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 23	00:05	 54,935k	9,927k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 24	00:09	 98,249k	9,835k	-3.09	1.Nxc7+ Bxc7 2.Kf3 a6 3.Ke2 Bd8 4.exd8Q+ Kxd8 5.Kf3 Kc7 6.Rh3 Kxc6 7.Rxg3 Nh6 8.Kf4 Rxg3 9.Kxg3 Nf5+ 10.Kf4 Nh4 11.g4 Ng6+ 12.Kg5 Nxe5 13.dxe5 d4 14.Kf4 dxc3 15.Ke3 Kd5 16.g5 Kxe5 17.Ke2 Kf5 18.Kd1 c2+ 19.Kd2 Kxg5 20.Kxc2 e5
 24	00:09	 98,249k	9,835k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 24	00:09	 98,249k	9,835k	 0.00	1.Kf3 Rg5 2.Ke3 Rg4 3.Ke2 Rg6
---------------------------------------------------------------------------
 25	00:25	 239,356k	9,517k	-3.38	1.Nxc7+ Bxc7 2.Ke3 Bb6 3.Kf3 a6 4.Ke3 Bd8 5.exd8R+ Kxd8 6.Kf3 Kc7 7.Rh3 Kxc6 8.Rxg3 Nh6 9.Kf4 Rxg3 10.Kxg3 Nf5+ 11.Kf4 Nh4 12.g3 Ng6+ 13.Kg4 Nxe5+ 14.dxe5 d4 15.Kf3 d3 16.Ke3 Kd5 17.g4 Kxe5 18.g5 Kf5
 25	00:25	 239,356k	9,517k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 25	00:25	 239,356k	9,517k	 0.00	1.Kf3 Rg5 2.Kf4 Rg6
---------------------------------------------------------------------------
 26	00:31	 295,994k	9,455k	-3.56	1.Nxc7+ Bxc7 2.Kf3 Ba5 3.Kf4 Bb6 4.Kf3 Bc7 5.Ke3 Bd8 6.exd8R+ Kxd8 7.Kf4 Kc7 8.Rh3 Kxc6 9.Rxg3 Nxf6 10.exf6 Rxf6+ 11.Ke3 Kb6 12.Rg7 Ka5 13.g4 Kxa4 14.g5 Rg6 15.Rxf7 Kb3 16.Kd2 a5 17.Rb7+ Ka3 18.Rb1 Rxg5 19.Ra1+ Kb2 20.Rxa5 Rg2+ 21.Ke3 Rg3+ 22.Kf4 Rg1 23.Ke5 Re1+ 24.Kd6 Kxc3 25.Kc5 Kd3 26.Ra2 c3 27.Rf2
 26	00:31	 295,994k	9,455k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 26	00:31	 295,994k	9,455k	 0.00	1.Kf3 Rg5 2.Kf4 Rg6
---------------------------------------------------------------------------
 27	00:36	 339,789k	9,430k	-3.54	1.Nxc7+ Bxc7 2.Kf3 a6 3.Ke3 Bd8 4.exd8Q+ Kxd8 5.Rh3 Kc7 6.Rh7 Nh6 7.Kd2 Kxc6 8.Kc1 Kd7 9.Kd2 Ke8 10.Rh8+ Ng8 11.Ke3 Kd8 12.Kf4 Kc7 13.Rh3 Nxf6 14.exf6 Kc6 15.Rxg3 Rxf6+ 16.Ke3 Kb6 17.Rg7 Ka5 18.g4 Kxa4 19.g5 Rg6 20.Rxf7 Kb3 21.Rb7+ Kxc3
 27	00:36	 339,789k	9,430k	 0.00	1.Ke3 Rg4 2.Ke2 Rg6
 27	00:36	 339,789k	9,430k	 0.00	1.Kf3 Rg5 2.Kf4 Rg6
---------------------------------------------------------------------------
 28	00:45	 428,743k	9,469k	-3.82	1.Nxc7+ Bxc7 2.Kf3 Bb6 3.Kf4 Ba5 4.Kf3 Bc7 5.Ke3 Bd8 6.exd8R+ Kxd8 7.Rh3 Kc7 8.Rh7 Nh6 9.Kd2 Kxc6 10.Kc2 Kd7 11.Kd2 Kd8 12.Kd1 Ke8 13.Kd2 Kf8 14.Rh8+ Ng8 15.Rh1 Nxf6 16.exf6 Rxf6 17.Re1 Ke7 18.Re3 Rf2+ 19.Re2 Rxe2+ 20.Kxe2 Kd7 21.Kf3 Kc6 22.Kg4 f6 23.Kh4 e5 24.dxe5 fxe5 25.Kxg3 d4 26.Kf3 dxc3 27.Ke2
 28	00:45	 428,743k	9,469k	 0.00	1.Kf3 Rg5 2.Kf4 Rg6
 28	00:45	 428,743k	9,469k	+M31	1.Ke3 Rg4 2.Ke2 Rg6 3.Kd1 Rg4 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd1 Rg4 15.Kc1 Rg6 16.Kc2 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kb8 28.Qxg6 Kb7 29.Qxg8 b5 30.Rh7+ Kb6 31.Qxe6+
---------------------------------------------------------------------------
 29	00:46	 442,807k	9,450k	-3.91	1.Nxc7+ Bxc7 2.Ke3 Bd8 3.exd8R+ Kxd8 4.Rh7 Nh6 5.Kd2 Kc7 6.Kc2 Kxc6 7.Kc1 Kc7 8.Kc2 Kd7 9.Kd2 Ke8 10.Rh8+ Ng8 11.Ke3 Kd8 12.Kf4 Kd7 13.Rh3 Kc6 14.Rxg3 Nxf6 15.Rxg6 Nh5+ 16.Kg5 fxg6 17.g4 Ng3 18.Kxg6 Ne2 19.g5 Nxd4 20.Kf6 Ne2 21.Kxe6 Nf4+ 22.Kf5 Nh5 23.Kg6 d4 24.Kf7 Ng3 25.g6 dxc3
 29	00:46	 442,807k	9,450k	+M31	1.Kf3 Rg5 2.Ke2 Rg6 3.Kd1 Rg4 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd1 Rg4 15.Kc2 Rg6 16.Kc1 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kb8 28.Qxg6 Kb7 29.Qxg8 b5 30.Rh7+ Kb6 31.Qxe6+
 29	00:46	 442,807k	9,450k	+M31	1.Ke3 Rg4 2.Ke2 Rg6 3.Kd2 Rg5 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd1 Rg4 15.Kc2 Rg6 16.Kc1 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kb8 28.Qxg6 Kb7 29.Qxg8 b5 30.Rh7+ Kb6 31.Qxe6+
---------------------------------------------------------------------------
 30	00:54	 515,100k	9,444k	-4.14	1.Nxc7+ Bxc7 2.Kf3 Bb6 3.Kf4 Ba5 4.Kf3 Bc7 5.Ke3 Bd8 6.exd8R+ Kxd8 7.Rh3 Kc7 8.Kf4 Kxc6 9.Rxg3 Nxf6 10.exf6 Rxf6+ 11.Ke3 Kb6 12.Rg7 Ka5 13.g4 Kxa4 14.g5 Rg6 15.Rxf7 Kb3 16.Rxa7 Rxg5 17.Kd2 Rg2+ 18.Ke3 Rg3+ 19.Kf4 Rg1 20.Ke3 Kxc3 21.Ra3+ Kb4 22.Ra8 Kb3 23.Ra5 Rg4 24.Ra6 Re4+ 25.Kf2
 30	00:54	 515,100k	9,444k	+M31	1.Kf3 Rg5 2.Ke2 Rg6 3.Kd1 Rg4 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd1 Rg4 15.Kc1 Rg6 16.Kc2 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kb8 28.Qxg6 Kb7 29.Qxg8 b5 30.Rh7+ Kb6 31.Qxe6+
 30	00:54	 515,100k	9,444k	+M31	1.Ke3 Rg4 2.Ke2 Rg6 3.Kd1 Rg4 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd2 Rg5 15.Kc1 Rg6 16.Kc2 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kb8 28.Qxg6 Kb7 29.Qxg8 b5 30.Rh7+ Kb6 31.Qxe6+
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 31	01:02	 591,111k	9,438k	-4.24	1.Nxc7+ Bxc7 2.Kf3 Ba5 3.Kf4 Bb6 4.Kf3 Bc7 5.Ke2 Bd8 6.exd8Q+ Kxd8 7.Rh7 Nh6 8.Kd1 Kc7 9.Kc1 Kxc6 10.Kc2 Kd7 11.Kd2 Ke8 12.Rh8+ Ng8 13.Ke3 Kd8 14.Rh7 Nxf6 15.exf6 Rxf6 16.Rg7 Kc7 17.a5 Kc6 18.Rxg3 Kb5 19.Rg8 Kxa5 20.g4 Ka4 21.g5 Rg6 22.Rf8 Kb3 23.Rxf7 Rxg5 24.Rxa7 Rg2 25.Kf3 Rg6
 31	01:02	 591,111k	9,438k	+M31	1.Kf3 Rg5 2.Ke2 Rg6 3.Kd2 Rg5 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd1 Rg4 15.Kc2 Rg6 16.Kc1 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kc6 28.Rh7 Ne7 29.Qxe7 Rg7 30.Rxg7 b5 31.Qxe6+
 31	01:02	 591,111k	9,438k	+M31	1.Ke3 Rg4 2.Ke2 Rg6 3.Kd2 Rg5 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd1 Rg4 15.Kc2 Rg6 16.Kc1 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kc6 28.Rh7 Ne7 29.Qxe7 Rg7 30.Rxg7 b5 31.Qxe6+
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 31	01:02	 593,044k	9,437k	-4.24	1.Nxc7+ Bxc7 2.Kf3 Ba5 3.Kf4 Bb6 4.Kf3 Bc7 5.Ke2 Bd8 6.exd8Q+ Kxd8 7.Rh7 Nh6 8.Kd1 Kc7 9.Kc1 Kxc6 10.Kc2 Kd7 11.Kd2 Ke8 12.Rh8+ Ng8 13.Ke3 Kd8 14.Rh7 Nxf6 15.exf6 Rxf6 16.Rg7 Kc7 17.a5 Kc6 18.Rxg3 Kb5 19.Rg8 Kxa5 20.g4 Ka4 21.g5 Rg6 22.Rf8 Kb3 23.Rxf7 Rxg5 24.Rxa7 Rg2 25.Kf3 Rg6
 32	01:02	 593,044k	9,437k	+M31	1.Kf3 Rg5 2.Ke2 Rg6 3.Kd2 Rg5 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd2 Rg5 15.Kc1 Rg6 16.Kc2 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kc6 28.Rh7 Ne7 29.Qxe7 Rg7 30.Rxg7 b5 31.Qxe6+
 32	01:02	 593,044k	9,437k	+M31	1.Ke3 Rg4 2.Ke2 Rg6 3.Kd2 Rg5 4.Kc2 Rg6 5.Kc1 Rg4 6.Kd1 Rg5 7.Kd2 Rg6 8.Ke2 Rg4 9.Ke3 Rg5 10.Kf3 Rg6 11.Kf4 a6 12.Ke3 Rg4 13.Ke2 Rg6 14.Kd2 Rg5 15.Kc1 Rg6 16.Kc2 Rg4 17.Kd1 Rg5 18.Kd2 Rg6 19.Ke2 Rg4 20.Ke3 Rg5 21.Kf3 Rg6 22.Kf4 Bb6 23.Nxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8Q+ Kxc7 27.Qxf7+ Kc6 28.Rh7 Ne7 29.Qxe7 Rg7 30.Rxg7 b5 31.Qxe6+

[peter]

Update your records, this one is a dual.

Well, even I yet could doubt the MultiPV=3 output to maybe having added 1 move to the shorter #30 in my .pgn you quoted, (didn't check again, but as far as I remember, Chest- Database said #30 too) it was and is a major dual anyhow, even if second one solution was or is 1 move longer to mate, because this is a study, not a mate in x- puzzle, you know?

[MOBMAT]

Well, part of our analysis is to weed out those positions/puzzles/studies that aren't quite ready for prime time.
If it was a Mate in X problem, then it could be restated to be a find the two moves that satisfy the Mate in X or find either of the two....
if the position is to be included in a test suite, then it should be removed or specified that it it is a dual.
Don't shoot the messenger! LOL

[peter]

If it was a Mate in X problem, then it could be restated to be a find the two moves that satisfy the Mate in X or find either of the two....
if the position is to be included in a test suite, then it should be removed or specified that it it is a dual.

Its' none of both. It's a study.

It's a matter of categories of compositions evaluated by judges.
A mate in x-problem is an other category to be published and judged than a study is, you see?

Arpad Rusz showed a study then, that was somewhat "cooked" by having two solutions, no matter if one solution was 1 or 2 or 3 moves longer to mate than the other one.

"Dual" has an other meaning as for studies as it has for test postions. A dual in a study is a second move of solution no matter of length to mate. Major Dual means dual at first move, Minor Dual at later moves.

Mate in x-problems are another sort of compostion with other kind of rules for judges or journals to publish them.

http://talkchess.com/forum3/viewtopic.p ... 63#p453963

The rest of the thread I then had with Arpad was somewhat ironically meant to get a difference of any kind out of the two solutions, well knowing, that it didn't count for judges and the "wearth" of the study at all.
So you simply took me two seriously, even if I really thought Ke3 being #30, not in 31.

Thanks for reviewing it, but it doesn't matter as for the purposes it was composed for, that's what I meant, you see?

BTW, I had a look into Chest Database in meantime and indeed, it's stored as #31 there too, so congrats!

[peter]

BTW, I had a look into Chest Database in meantime and indeed, it's stored as #31 there too

And it's much easier nowadays to keep way to mate in hash backward with SF dev. then it was then, of course, position after 1.Ke3:

N3k1nR/p1p1Pp2/2P1pPr1/b2pP3/P1pP4/2P1K1p1/6P1/8 b - - 0 1

Analysis by Stockfish 040820:

1...Tg4 2.Ke2 Tg6 3.Kd2 Tg5 4.Kc2 Tg6 5.Kc1 Tg4 6.Kd1 Tg5 7.Kd2 Tg6 8.Ke2 Tg4 9.Ke3 Tg5 10.Kf3 Tg6 11.Kf4 a6 12.Kf3 Tg5 13.Ke2 Tg6 14.Kd1 Tg4 15.Kc1 Tg6 16.Kc2 Tg4 17.Kd1 Tg5 18.Kd2 Tg6 19.Ke2 Tg4 20.Ke3 Tg5 21.Kf3 Tg6 22.Kf4 Lb6 23.Sxb6 a5 24.Ke3 cxb6 25.c7 Kd7 26.e8D+ Kxc7 27.Dxf7+ Kb8 28.Dxg6 Ka7 29.Dxg8 Kb7 30.Dg7+ Ka6 31.Ta8#
+- (#30) Tiefe: 77/61 00:00:39 1281MN

Suboptimal move in my .pgn then was 7...Rg4 instead of ...Rg6, first one #30 all in all, second one in 31.
Updated.