Black's Rook doesn't dare leave the 8th rank, or 2.Rh8+ mates.
Nor can it stray too far from the center; on moves like 1...Rxb8 or 1...Rg8, White has 2.Qh3+ Kg1 3.Bd4#
The two main variations, therefore, are:
1...Re8 2.Ne7! and Black must allow either 3.Rh8# or 3.Rh6#
1...Rf8 2.Rf7! and Black must allow either 3.Rh8# or 3.Rf1#.
Try: 1.Rc8? Rf8! 2.Rf5 Rf6!! and White has no mate.
If Rh6 then Rxh6#
If Rxc8, Re8, Rf8, or Rg8 then Ne3
If Rd7, Rd5, Rd3, or Rd1 then Rh8#
If Rd6 or Rd4 then Rh8+ folled by RxR#
If Rd2, then Rh8+ followed by QxR#
Edit: Damn it, BigDoggProblem! You beat me to it 🙂
The only thing left I can think of is 1. Qg4 to stop stalemate threats, then it depends on what black does, but assuming it is move the rook it should be possible to move a knight or pawn to open a line for a rook in such a way that black can't get out of the checkmate. eg 1. Qg4 Rh8 (to stop rooks getting to the h-file) 2. Ne3 Rh2 3. Qd1#, but I haven't gone through all of black's possible moves so it could be flawed.
Edit: Although Rc8 seems better, posted before the above.
Rc8
if Rxc8 Ne1 anything Qg2#
if R moves off its back rank then Rh8
if Re8 Ne7 or Ne3 gives mate next move
if Rf8 or Rg8 or Rh8 then Rf5 gives mate next move
If Rh6 then Rxh6#
If Rxc8, Re8, Rf8, or Rg8 then Ne3
If Rd7, Rd5, Rd3, or Rd1 then Rh8#
If Rd6 or Rd4 then Rh8+ folled by RxR#
If Rd2, then Rh8+ followed by QxR#
Edit: Damn it, BigDoggProblem! You beat me to it 🙂
1.Rc8? Rf8! 2.Ne3 Rf2! is a typical refutation of many of the lines involving Ne3 or Ne1 by White, to threaten Qg2#.
As in so many of the failing variations, the pesky black Rook is able to hang out very close to its King, slowing down white attacks from every direction.
Originally posted by BigDoggProblem 1.Rc8? Rf8! 2.Ne3 Rf2! is a typical refutation of many of the lines involving Ne3 or Ne1 by White, to threaten Qg2#.
As in so many of the failing variations, the pesky black Rook is able to hang out very close to its King, slowing down white attacks from every direction.
The problem with Rb8 is Rxb8 and then Rb4+ which is drawn as black eventually has to take the rook, if you are right about Rc8 not working either we are back to 1. Qg4.
Edit: read your post more carefully, Rb8 seems to work.
Originally posted by BigDoggProblem 1.Rc8? Rf8! 2.Ne3 Rf2! is a typical refutation of many of the lines involving Ne3 or Ne1 by White, to threaten Qg2#.
As in so many of the failing variations, the pesky black Rook is able to hang out very close to its King, slowing down white attacks from every direction.
Oh, okay.
So, 1. Rc8 Rf8 2. Qh3+ Kg1 3. Bd4#? I didn't see that line.
Originally posted by BLReid I let Fritz8 take a go at it, and the best it comes up with is #4. If Fritz can't do it, then I know I can't. I give up.
Because Fritz plays a move resulting in mate in 4 doesn't mean that there isn't a faster mate. In fact, Fritz plays for the first mate that it sees, without searching for a faster mate.
Originally posted by BigDoggProblem [fen]3r4/2R3N1/R1N5/1R4P1/K1P5/1B4Q1/1BN5/7k[/fen]
[b]1.Rb8!! (zugzwang)
Black's Rook doesn't dare leave the 8th rank, or 2.Rh8+ mates.
Nor can it stray too far from the center; on moves like 1...Rxb8 or 1...Rg8, White has 2.Qh3+ Kg1 3.Bd4#
The two main variations, therefore, are:
1...Re8 2.Ne7! and Black must allow either 3.Rh8# or 3.R ...[text shortened]... ack must allow either 3.Rh8# or 3.Rf1#.
Try: 1.Rc8? Rf8! 2.Rf5 Rf6!! and White has no mate.[/b]
Originally posted by ThudanBlunder Because Fritz plays a move resulting in mate in 4 doesn't mean that there isn't a faster mate. In fact, Fritz plays for the first mate that it sees, without searching for a faster mate.
Good to know. We still don't have a viable 3 move forced mate.
EDIT- Nevermind, looks like BigDogg has gotten it.