White to move and mate

DjVortex

I just had this position in a game. I was certain there was a mate somehow, and I spent quite a lot of time reading, but I just were not strong enough to find it (and ran out of time). A stronger player than me probably sees it much easier. In my defense, though, it takes even Stockfish a bit of time to find a mate.

Technically (according to SF) this is mate in 12, but much of the later moves in that sequence are just trivial struggling moves that just delay the mate, and it's the first moves that are crucial, so I don't really know how to classify this. I suppose just a "white to move and mate (in a relatively short amount of moves, at most 12 of them)" ought to suffice.

Optimissed

Hello .... in reality, of course, white can just win all of black's pawns and so has no need for a mate, and yet there does seem to be an easy mate available for white, starting with Bb1 and then playing Rb2 and Ra2 ++, so the question is just how much black can slow white down by playing ...d5 and trying to gain entry for the R by that route. If we get ...d5 c5 and then d4+, white's mating position is prevented. White could try to blockade the d pawn by playing 1. Kd4 but black's pawns dislodge the K. So, I would play
1. c5 ... d5
2. cd ...Rxd6
3. Bb1 ...Rd5
4. Rb2

But black has 1. c5 ...Ka2
2. Bb1 ...Ka1
3. Rb2 ...d5
4. Kc2 and black cannot prevent mate. So perhaps black has other ways of slowing white. I can't be bothered to look for them. 1. c5 ...d6 introduces further possibilities.

DjVortex

According to Stockfish analysis, Bb1 is not losing per se, but there doesn't seem to be any mate any time in the near future. If instead c5, it can find a mate in 19, so it's much longer. Thus there's a path to faster victory.

Optimissed

So how does Stockfish propose that a mate can be avoided after the moves I proposed? Black's King cannot get away and Black can only give up his R in some way.

Optimissed

Can you show the analysis after 1. c5.

Tejaswiniqueen0607

DjVortex wrote:

I just had this position in a game. I was certain there was a mate somehow, and I spent quite a lot of time reading, but I just were not strong enough to find it (and ran out of time). A stronger player than me probably sees it much easier. In my defense, though, it takes even Stockfish a bit of time to find a mate.

Technically (according to SF) this is mate in 12, but much of the later moves in that sequence are just trivial struggling moves that just delay the mate, and it's the first moves that are crucial, so I don't really know how to classify this. I suppose just a "white to move and mate (in a relatively short amount of moves, at most 12 of them)" ought to suffice.

1. c5

DjVortex
Optimissed wrote:

So how does Stockfish propose that a mate can be avoided after the moves I proposed? Black's King cannot get away and Black can only give up his R in some way.

For Bb1 as the first move:

If 1. Bb1 d5 2. Rb2, then as you pointed out, d4+ 3. Kc2 e5. The position is evaluated as almost completely even now (thus, as far as SF is concerned, all advantage has now been conceded.)

The best evaluation continues as: 4. Rb6 e4 5. Kd2 d3 6. c5 f5, etc.

Instead of 2. Rb2, this is the best line evaluated by SF:

1. Bb2 d5 2. c5 e5 3. Rb6 Ra8 4. Rxc6 Ra5 5. Bc2 Rb5 6. Rc8 Rb4. It evaluates this line at about +4 (clearly winning, but no mate in sight).

As for c5 as the first move:

 

Optimissed

Yes and as I pointed out, black gives up the rook quite early. I agree that the approach is not 31, Bb1. Too slow as white is liable to be checked.

DjVortex

The fastest way to mate starts with Rb1.

Optimissed

That was the first option I thought of, within a few seconds, and possibly what I might have played in a blitz game but it seemed more difficult to work out whereas c5 seemed to lead to mate much more easily. But it took me about five minutes to find c5.

DjVortex

Rb1 was what I played in the game in question, but in the end I was unable to find the mate and I ran out of time.

This is the mate in 12 that SF suggests:

 

Optimissed

Thanks