Fortresses

[Vinvin]

Here is another one:

[d]4KBbn/5p2/6p1/3k1P2/3N2P1/7p/8/8 w - - 0 0
1. f6 h2 2. g5 h1=Q 3. Bh6 Kxd4 4. Kf8 *

Still stockfish dev think it's ahead +10

SF finds 1.Nf3 is draw. Nf3 is selected on depth=1

Code: Select all

Stockfish_16033114_x64_modern:
 1/1	00:00	 173	87k	-0,87	1.Nf3
 2/2	00:00	 918	459k	-1,08	1.Nf3 f6
 3/3	00:00	 1k	657k	-1,47	1.Nf3 f6 2.Nh2
 4/4	00:00	 2k	829k	-1,47	1.Nf3 f6 2.Nh2 gxf5
 5/5	00:00	 3k	1 526k	-1,14	1.Nf3 gxf5 2.gxf5 Bh7 3.f6
 6/6	00:00	 4k	2 146k	-1,22	1.Nf3 gxf5 2.gxf5 Bh7 3.f6 Bb1
 7/8	00:00	 8k	2 669k	-0,65	1.Nf3 gxf5 2.gxf5 f6 3.Bg7 Ke4 4.Nd2+ Kxf5
 8/9	00:00	 16k	1 986k	-1,02	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Bxf6 Ke4
 9/12	00:00	 23k	1 620k	-0,72	1.Nf3 f6 2.Bg7 Nf7 3.fxg6 Ne5 4.Nh2 Nxg6 5.Bxf6
 10/13	00:00	 37k	1 439k	-0,81	1.Nf3 f6 2.Bg7 Nf7 3.Nh2 Nd6+ 4.Kf8 Bh7 5.fxg6 Bxg6 6.Ke7 Nf7 7.Kxf6
 11/15	00:00	 48k	1 561k	-0,81	1.Nf3 f6 2.Bg7 Nf7 3.Kf8 Ne5 4.Nh2 Bh7 5.fxg6 Bxg6 6.Ke7 Nf7 7.Kxf6
 12/20	00:00	 129k	3 077k	-1,15	1.Nf3 f6 2.Nh2 gxf5 3.Bg7 Nf7 4.Kf8 fxg4 5.Nxg4 Ne5 6.Nf2 h2 7.Kxg8
 13/22	00:00	 183k	3 970k	-1,14	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Kf7 Nd6+ 8.Ke7
 14/23	00:00	 218k	4 270k	-1,12	1.Nf3 gxf5 2.gxf5 f6 3.Bg7 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Ke7 Bxf5 8.Bg7 Nc5 9.Kf7 Bh7 10.Kf6 Ne4+ 11.Ke7
 15/24	00:00	 242k	4 575k	-1,02	1.Nf3 gxf5 2.gxf5 f6 3.Bg7 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Ke7 Bxf5 8.Bg7 Nc5 9.Bc3 Be4 10.Bb4
 16/27	00:00	 468k	6 679k	-0,96	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Bb2 Bxf5 8.Kf7 Kd6 9.Bd4 Bd7 10.Kg6 Ke6 11.Kh5 Kf5 12.Kh4 Kf4 13.Nf1
 17/28	00:00	 532k	7 003k	-0,92	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Bb2 Bxf5 8.Kf7 Nc5 9.Kf6 Ke4 10.Kg5 Nd3 11.Bg7 Nf4 12.Kh4 Bd7 13.Bb2 Be6
 18/29	00:00	 646k	7 341k	-0,93	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Bb2 Bxf5 8.Ke7 Bc8 9.Kf7 Nc5 10.Kf6 Ke4 11.Ba3 Ne6 12.Bd6 Bd7 13.Kg6 Nd4 14.Kg5 Kd5
 19/29	00:00	 782k	7 817k	-0,91	1.Nf3 gxf5 2.gxf5 f6 3.Bg7 Nf7 4.Kf8 Ng5 5.Nh2 Bh7 6.Bxf6 Ne4 7.Bb2 Bxf5 8.Kf7 Ng3 9.Kf6 Bd7 10.Kg5 Ne2 11.Bf6 Be6 12.Kh4 Ke4 13.Bb2 Kf4 14.Nf1
 20/36	00:00	 1 447k	9 523k	-0,92	1.Nf3 gxf5 2.gxf5 f6 3.Bg7 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Ke4 7.Kxf6 Bxf5 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Bf4 Nf5+ 14.Kg4 Nd6+ 15.Kh4
 21/38	00:00	 2 348k	10 578k	-0,85	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Bf4 Nf5+ 14.Kg5 Be6 15.Ng4 Nd4 16.Nh2 Nb3 17.Ng4 Na5 18.Kh4 Kf3
 22/41	00:00	 2 453k	10 620k	-0,85	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Bf4 Nf5+ 14.Kg5 Be6 15.Ng4 Nd4 16.Nh2 Ne2 17.Be5 Ng3 18.Kh4 Nf5+ 19.Kg4 Ne3+ 20.Kg5 Bd7 21.Bf4
 23/41	00:00	 3 418k	7 496k	-0,82	1.Nf3 gxf5 2.gxf5 f6 3.Bg7 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Bf4 Nf5+ 14.Kg5 Be6 15.Ng4 Nd4 16.Nh2 Bc4 17.Be5 Nc6 18.Bd6 Nd8 19.Kh4 Be6 20.Ng4
 24/42	00:00	 6 289k	8 675k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Bc8 14.Kh4 Be6 15.Bc7 Bd7 16.Be5 Bf5 17.Kg5 Be6 18.Kh4 Nd5
 25/42	00:00	 7 312k	8 777k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Bc8 14.Kh4 Be6 15.Bc7 Bd7 16.Be5 Bf5 17.Kg5 Be6 18.Kh4 Nd5 19.Ng4 Bf5 20.Bd6
 26/47	00:00	 7 793k	8 896k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Bc8 14.Kh4 Be6 15.Bc7 Bd7 16.Be5 Bf5 17.Kg5 Be6 18.Kh4 Bc8 19.Bf4 Nd5 20.Be5 Bf5 21.Ng4
 27/47	00:00	 8 460k	9 049k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Bc8 14.Kh4 Be6 15.Bc7 Bd7 16.Be5 Bf5 17.Kg5 Be6 18.Bc7 Nd5 19.Be5 Nb6 20.Ng4 Nc4 21.Bf4 Na5
 28/47	00:01	 12 459k	8 267k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Bc8 14.Kh4 Be6 15.Bc7 Bd7 16.Be5 Bf5 17.Kg5 Be6 18.Bc7 Nd5 19.Be5 Nb4 20.Bd6 Nc2 21.Ng4 Nd4 22.Nh2
 29/47	00:01	 14 835k	8 320k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Nd5 14.Kh4 Ne7 15.Kg5 Nc6 16.Bd6 Bc8 17.Ng4 Nd4 18.Ne3+ Kf3 19.Nf1 Kf2 20.Nh2 Kg2 21.Be5 Ne6+ 22.Kh4 Nd8 23.Bd6
 30/52	00:02	 19 794k	7 867k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Nd5 14.Kh4 Ne7 15.Kg5 Nc6 16.Bd6 Bc8 17.Ng4 Nd4 18.Ne3+ Kf3 19.Nf1 Nf5 20.Nh2+ Kg2 21.Be5 Ne7 22.Bf4 Nd5 23.Be5 Nb4 24.Bd6 Nd3
 31/52	00:02	 23 052k	7 819k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kh5 Nd5 14.Kh4 Ne7 15.Kg5 Nc6 16.Bd6 Bc8 17.Ng4 Nd4 18.Ne3+ Kf3 19.Nf1 Nf5 20.Nh2+ Kg2 21.Be5 Ne7 22.Bf4 Nd5 23.Be5 Ne3 24.Kh4 Be6 25.Bc7 Bd7
 32/52	00:03	 28 409k	7 578k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kg5 Be6 14.Kh4 Nc4 15.Bf4 Na5 16.Ng4 Nc6 17.Nh2 Ne7 18.Kg5 Bd7 19.Be5 Nc6 20.Bd6 Bc8 21.Ng4 Nd4 22.Ne3+ Kf3 23.Nf1 Nf5 24.Nh2+ Kg2 25.Be5
 33/52	00:06	 46 025k	6 924k	-0,75	1.Nf3 f6 2.Bg7 gxf5 3.gxf5 Nf7 4.Kf8 Ne5 5.Nh2 Bh7 6.Ke7 Bxf5 7.Kxf6 Ke4 8.Kg5 Ng4 9.Nf1 Kf3 10.Kh4 Ne3 11.Nh2+ Kg2 12.Be5 Bd7 13.Kg5 Be6 14.Kh4 Nc4 15.Bf4 Na5 16.Ng4 Nc6 17.Nh2 Ne7 18.Kg5 Bd7 19.Be5 Nc6 20.Bd6 Nd4 21.Be5 Nb3 22.Ng4 Nd2 23.Kf4 Nc4 24.Bc7
 34/53+	00:09	 66 737k	6 707k	-0,68	1.Nf3
 34/53+	00:11	 83 692k	7 084k	-0,61	1.Nf3
 34/53+	00:20	 179 070k	8 575k	-0,15	1.Nf3
 34/53	00:26	 245 369k	9 210k	-0,11	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Nd6+ 5.Kf8 Bh7 6.Bxf6 Bxf5 7.Kg7 Be4 8.Kh6 Bg2 9.Kh5 Ne4 10.Bb2 Nf2 11.Kh4 Ke4 12.Kg3 Nh1+ 13.Kg4 Ke3 14.Bc1+ Ke2 15.Bf4 Nf2+ 16.Kg3 Ne4+ 17.Kg4 Kf2 18.Be5 Nd2 19.Bd4+ Ke2 20.Bc3 Nb3 21.Kg3 Nc5 22.Bd4 Ne6 23.Ng4
 35/53+	00:31	 290 344k	9 283k	-0,04	1.Nf3
 35/53	00:32	 297 068k	9 252k	 0,00	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Ne5 5.Ke7 Ke4 6.Kxf6 Nf3 7.Ng4 Kf4 8.Nf2 h2 9.Bf8 Kg3 10.Bd6+ Kg2 11.Bxh2 Nxh2
 36/53	00:32	 298 860k	9 229k	 0,00	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Ne5 5.Ke7 Ke4 6.Kxf6 Nf3 7.Ng4 Kf4 8.Nf2 h2 9.Bf8 Kg3 10.Bd6+ Kg2 11.Bxh2 Nxh2
 37/53	00:33	 311 213k	9 249k	 0,00	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Ne5 5.Ke7 Ke4 6.Kxf6 Nf3 7.Ng4 Kf4 8.Nf2 h2 9.Bf8 Kg3 10.Bd6+ Kg2 11.Bxh2 Nxh2
 38/53	00:35	 324 768k	9 207k	 0,00	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Ne5 5.Ke7 Ke4 6.Kxf6 Nf3 7.Ng4 Kf4 8.Nf2 h2 9.Bf8 Kg3 10.Bd6+ Kg2 11.Bxh2 Nxh2
 39/53	00:37	 340 378k	9 037k	 0,00	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Ne5 5.Ke7 Ke4 6.Kxf6 Nf3 7.Ng4 Kf4 8.Nf2 h2 9.Bf8 Kg3 10.Bd6+ Kg2 11.Bxh2 Nxh2
 40/53	00:38	 343 944k	9 020k	 0,00	1.Nf3 f6 2.Nh2 gxf5 3.gxf5 Nf7 4.Bg7 Ne5 5.Ke7 Ke4 6.Kxf6 Nf3 7.Ng4 Kf4 8.Nf2 h2 9.Bf8 Kg3 10.Bd6+ Kg2 11.Bxh2 Nxh2

[rabbits23]

Solution Jon?
Allan

[Nordlandia]

Please spesify which FEN

[rabbits23]

Jon : Can you provide the 14 moves to the solution in PGN format?
Thanks Allan

[rabbits23]

Whoops sorry Jon, late night.In the fortress puzzles you have one which you
say is forced mate in 14. that's the one I'm curious about.
Allan

[rabbits23]

I can't get anything right tonight! In the fortress chess puzzles you have one
that is forced mate in 13 moves. I'd appreciate the solution to that.
Thanks again
Allan

[Nordlandia]

Well, it can't be a fortress when white can force mate

[pgn][Event "?"]
[Site "?"]
[Date "????.??.??"]
[Round "?"]
[White "New game"]
[Black "?"]
[Result "*"]
[SetUp "1"]
[FEN "6bn/p4p1k/rp3Pp1/rp2BBP1/1p6/pK6/P2P4/8 w - - 0 1"]
[PlyCount "25"]

1. Bc8 ({Komodo 9.42 64-bit:} 1. Bc8 Ra4 2. Bd6 R6a5 3. Ba6 Rxa6 4. Bf8 R4a5 5.
Bg7 Ra4 6. Bxh8 Kxh8 7. d4 R4a5 8. d5 Ra4 9. d6 R4a5 10. d7 Ra4 11. d8=Q R6a5
12. Qf8 Kh7 13. Qg7# {#13/35}) 1... Ra4 2. Bd6 R6a5 3. Ba6 Rxa6 {SugaR 2.5 64
BMI2:} 4. Bf8 R6a5 5. Bg7 Ra6 6. d4 R6a5 7. d5 a6 8. Bxh8 Kxh8 9. d6 Bh7 10. d7
Bg8 11. d8=Q Kh7 12. Qf8 Kh8 13. Qg7# {#10/127} *

[/pgn]

[rabbits23]

Very true Jon but then why did you include it in the list of fortress positions? Still thanks for the solution. Houdini 4 announces mate in 10 after me feeding it 1 Bc8 Ra4 2Bd6 R6a5.
Allan