Checkmate in 4

Originally posted by Bad wolf
If black responds to Bxc6 with d1Q
1. Bxc6 d1B
2. gxf8B (this avoids stalemate problem with queen)
Qd4+ (delays checkmate)
3. exd4 Kxf6 (black's only legal move)
4. d5#

Yeah, yeah, this has been posted before. But what if
1.Bxc6 d1=B
or 1.Bxc6 d1=N
?

Originally posted by Mephisto2
Yeah, yeah, this has been posted before. But what if
1.Bxc6 d1=B
or 1.Bxc6 d1=N
?

Read my posts on the previous page...

I said the following:

If black responds with d1B
1. Bxc6 d1B
2. gxf8R Kd6 (black's only legal move)
3. Qd2+ Kxc7
4. Qd8#
There are others move for both black and white instead of 3. Kxc7 4.Qd8#
But all are checkmate in one move.

If black responds with d1N
1. Bxc6 d1N
2. gxf8Q Nxb2+ (other moves available for black but making little difference)
3. Qxb2 c1Q (piece promotion is black's only legal move)
4. c8Q#

Originally posted by Bad wolf
Read my posts on the previous page...

I said the following:

If black responds with d1B
1. Bxc6 d1B
2. gxf8R Kd6 (black's only legal move)
3. Qd2+ Kxc7
4. Qd8#
There are others move for both black and white instead of 3. Kxc7 4.Qd8#
But all are checkmate in one move.

If black responds with d1N
1. Bxc6 d1N
2. gxf8Q Nxb2+ (other move ...[text shortened]... making little difference)
3. Qxb2 c1Q (piece promotion is black's only legal move)
4. c8Q#

You are correct - my apologies. That concludes the problem. I owe you the source: Peter Hofman, dedicated to Tim Krabbé, published in Schach, september 2005.