Series selfmate in 42

SER-S#42

White makes 42 consecutive moves (without check - only the last move may be a check) to reach a position in which Black is forced to mate White in one move.

1.Ke3 2.e8=N 3.Nxf6 4.Ne4 5.f6 6.f7 7.f8=Q 8.Qxb8 9.Qf4 10.b8=B 11.Bxa7 12.Be4 e1=Q#

I believe this results in:


as this is not even close to forty two, I must be misunderstanding something

Originally posted by preachingforjesus
1.Ke3 2.e8=N 3.Nxf6 4.Ne4 5.f6 6.f7 7.f8=Q 8.Qxb8 9.Qf4 10.b8=B 11.Bxa7 12.Be4 e1=Q#

I believe this results in:
[fen]8/8/P6p/7P/p2BNQ1p/4Kp2/P1k2P1P/4q1n1[/fen]

as this is not even close to forty two, I must be misunderstanding something

I think the word "force" is important. In your position Black can also move the a-pawn, the knight and the king instead of promoting.

edit: oh and another problem i just noticed is, that black doesnt have to promote to queen. that makes it even more difficult.

Got it.

Originally posted by SwissGambit
Got it.

S'D (SwissGambit)

Ive gotten to 45 in about 6 different ways. For example:

1.e8=N 2.Nxf6 3.Ne4 4.f6 5.f7 6.f8=R 7.Rxf3 8.Ra3 9.Rxa4 10.Rb4 11.Rb1 12.Ra1 13.f4 14.f5 15.f6 16.f7 17.f8=B 18.Bxh6 19.Be3 20.h6 21.h7 22.h8=Q 23.Qxh4 24.Qe1 25.h4 26.h5 27.h6 28.h7 29.h8=Q 30.Qxb8 31.Qe5 32.b8=B 33.Bxa7 34.Bc5 35.a7 36.a8=B 37.Bd5 38.Bc4 39.a4 40.a5 41.a6 42.a7 43.a8=Q 44.Qad5

45.Qxe2+ Nxe2#

Can some one show me what i'm missing

edit :: I'v just notice The piece on c4 must be a knight instead of a bishop

Originally posted by preachingforjesus
Ive gotten to 45 in about 6 different ways. For example:

1.e8=N 2.Nxf6 3.Ne4 4.f6 5.f7 6.f8=R 7.Rxf3 8.Ra3 9.Rxa4 10.Rb4 11.Rb1 12.Ra1 13.f4 14.f5 15.f6 16.f7 17.f8=B 18.Bxh6 19.Be3 20.h6 21.h7 22.h8=Q 23.Qxh4 24.Qe1 25.h4 26.h5 27.h6 28.h7 29.h8=Q 30.Qxb8 31.Qe5 32.b8=B 33.Bxa7 34.Bc5 35.a7 36.a8=B 37.Bd5 38.Bc4 39.a4 40.a5 41.a6 42.a7 43.a8=Q ...[text shortened]... at i'm missing

edit :: I'v just notice The piece on c4 must be a knight instead of a bishop

That's the right idea. What you need to do now is work on efficiency. For example, the sequence 6.f8R 7.Rxf3 8.Ra3 9.Rxa4 10.Rb4 11.Rb1 is a lot of wasted moves with the White Rook. 3 of the moves are just 'setup' moves that do not capture a black pawn or control a necessary square around one of the Kings.

Think of it this way. You MUST promote all the pawns to set up the selfmate at the end. It will take 25 moves just to get them all to the promotion rank. 42-25 = 17 moves. 17 moves divided by 8 pieces = 2 moves and change. You're allowed a mere 2 moves per promoted piece - and for most, you'll need one to capture a black pawn, and another to move away and control square(s) around a King.

Originally posted by SwissGambit
That's the right idea. What you need to do now is work on efficiency. For example, the sequence 6.f8R 7.Rxf3 8.Ra3 9.Rxa4 10.Rb4 11.Rb1 is a lot of wasted moves with the White Rook. 3 of the moves are just 'setup' moves that do not capture a black pawn or control a necessary square around one of the Kings.

Think of it this way. You MUST promote all th ...[text shortened]... one to capture a black pawn, and another to move away and control square(s) around a King.

The big reason I kept coming up long Is the rook on a1 doesn't need to go to the back rank, just to the b-file; which reduces an earlier attemp by percicely 3 moves. and looks like:

1.e8=N 2.Nxf6 3.Nd5 4.f6 5.f7 6.f8=Q 7.Qxf3 8.Qg2 9.f4 10.f5 11.f6 12.f7 13.f8=B 14.Bxh6 15.Be3 16.h6 17.h7 18.h8=R 19.Rxh4 20.Re4 21.h4 22.h5 23.h6 24.h7 25.h8=Q 26.Qxb8 27.Qe5 28.b8=B 29.Bxa7 30.Bc5 31.a7 32.a8=R 33.Rxa4 34.Rb4 35.a4 36.a5 37.a6 38.a7 39.a8=N 40.Nb6 41.Nc4 42.Qxe2+ Nxe2#

Originally posted by preachingforjesus
The big reason I kept coming up long Is the rook on a1 doesn't need to go to the back rank, just to the b-file; which reduces an earlier attemp by percicely 3 moves. and looks like:

1.e8=N 2.Nxf6 3.Nd5 4.f6 5.f7 6.f8=Q 7.Qxf3 8.Qg2 9.f4 10.f5 11.f6 12.f7 13.f8=B 14.Bxh6 15.Be3 16.h6 17.h7 18.h8=R 19.Rxh4 20.Re4 21.h4 22.h5 23.h6 24.h7 25.h8=Q 26 ...[text shortened]... 37.a6 38.a7 39.a8=N 40.Nb6 41.Nc4 42.Qxe2+ Nxe2#

[fen]8/8/8/2BNQ3/1RNKR3/4B3/2k1n3/8[/fen]

Congrats, but how much time did you spend on that?!

Originally posted by preachingforjesus
The big reason I kept coming up long Is the rook on a1 doesn't need to go to the back rank, just to the b-file; which reduces an earlier attemp by percicely 3 moves. and looks like:

1.e8=N 2.Nxf6 3.Nd5 4.f6 5.f7 6.f8=Q 7.Qxf3 8.Qg2 9.f4 10.f5 11.f6 12.f7 13.f8=B 14.Bxh6 15.Be3 16.h6 17.h7 18.h8=R 19.Rxh4 20.Re4 21.h4 22.h5 23.h6 24.h7 25.h8=Q 26 ...[text shortened]... 37.a6 38.a7 39.a8=N 40.Nb6 41.Nc4 42.Qxe2+ Nxe2#

[fen]8/8/8/2BNQ3/1RNKR3/4B3/2k1n3/8[/fen]

Well done.

Note that white promoted exactly two of each kind of piece.