21 October 2011

After the key

It was rather by chance that I became curious and searched for examples where the twinning is achieved by taking the position that arises after the key move — another type of continuous problems. I found a lot of compositions! Many of them are so-called perpetua mobilia. This expression perpetuum mobile or Pauly theme is named after the German-Romanian problemist Wolfgang Pauly (1876-1934). There, you have the key move of solution a) that leads to the position b) the key move of which in turn leads to a). As a consequence, the set play of one part is the solution of the other part after the key move (see the following example).

Jan Kubecka
feenschach 01-03/1976
Commendation
34th TT (B)
[8/5P1P/6k1/6B1/8/6K1/8/8]
  h#2*(4+1)  
a) Diagram
b) after the key

The solution is
a) *1. - f8=Q 2. Kh5 Qh6# and 1. Kg7 f8=N 2. Kh8 Bf6#
b) *1. - f8=N 2. Kh8 Bf6# and 1. Kg6 f8=Q 2. Kh5 Qh6#.

I am not so crazy about those perpetua mobilia, though there are very many of them. Still, there is an abundance of other chess problems left featuring those "after the key" twins. Most of them are helpmates, but I managed to spot some directmate and selfmate compositions, as well. I hope you enjoy the choice I've made.


  1György Bakcsi  
Probleemblad, 1971
2nd Prize
[3R4/2pP3p/2Pp3R/3k4/1P4N1/3B1p2/P3pQ2/4K3]
  #2(10+6)  
a) Diagram
b)-e) after the key of a)-d)

  2Frank Christiaans  
Die Schwalbe 06/2001
 
[2Q5/6Pp/5N1p/2NP3B/2P5/1P6/1Pk2P2/R3K3]
  #2*(12+3)  
a) Diagram
b) after the key

  3Horst Bäcker  
Problemkiste 12/2008
 
[8/2p4Q/p1p1k3/K1P5/8/5p2/5P1p/B5nR]
  #4(6+7)  
a) Diagram
b) after the key

Solutions
1a) 1. a4! Kxc6 2. Be4#
b) 1. a5! Kxc6 2. Qxf3#
c) 1. a6! Kxc6 2. Qc5#
d) 1. a7! Kxc6 2. a8=B/Q#
e) 1. a8=N! Kxc6 2. Qxf3#
That's also a way to demonstrate an Excelsior! The helpmate No. 9 below enhances this effect.
2a) 1. Nd3! (Z) Kxb3 / Kxd3 2. Bd1 / 0-0-0#
b) *1. - Kxb3 / Kxd3 2. Bd1 / 0-0-0#
1. Qe8! (Z) Kxb3 / Kxd3 2. Qa4 / Qe4# (0-0-0??)
The key of a) gives two flights. Position b) provides a retroanalytically motivated dual avoidance. The last move was Kb1-/xc2 which proves that the wR had already moved and thus castling long is forbidden.
3a) 1. Rxh2? Nh3 2. Rxh3 Kd5 3. Rh5+ Ke6 4. ?
1. Bh8! Kd5 2. Qf5+ Kc4 3. Qe4+ Kxc5 / Kb3 4. Qd4 / Qa4#
1. - Ne2 2. Rd1 (thr. Qd7#) Nd4 3. Rxd4 h1=Q 4. Qd7#
b) 1. Ba1? Ne2 2. Rd1 Nd4! 3. ?
1. Rxh2! Nh3 2. Rxh3 Kd5 3. Rh5+ Ke6 / Kc4 4. Re5 / Qc2#
The try of a) is the solution of b), taking back the key move of a) is the try of b).


  4Baruch Lender  
Die Schwalbe 02/1983
 
[8/2p2Qp1/R1bk2Pp/4pK1P/pP4p1/pR1N2B1/qp6/bN6]
  s#2(10+12)  
a) Diagram
b) after the key

  5Gunter Jordan  
Schach 03/2009
5th Honourable Mention
[2Q5/1PR5/pk6/pb6/P1p5/2p5/2P2r2/1R4BK]
  s#5(8+7)  
a) Diagram
b) after the key

Solutions
4a) 1. Nf2! Qxb3 2. Qe6+ Qxe6#
1. - Qxb1+ 2. Ne4+ Qxe4#
1. - axb3 2. Nxg4 Qxb1#
b) 1. Nxg4! Qxb3 2. Qe6+ Qxe6#
1. - Qxb1+ 2. Rd3+ Qxd3#
1. - axb3 2. Bh2 Qxb1#
Observe the different continuations after Qxb1+ and axb3.
5a) 1. Rh7! Ka7 2. b8=R+ Bd7 3. R1b5! axb5 4. Rb7+ Ka6 5. Qc6+ Bxc6#
b) 1. Rh8! Ka7 2. b8=B+ Kb6! 3. Qxc4 Kb7 4. Qc7+ Ka8 5. Qc6+ Bxc6#
Different underpromotions.


  6Fadil Abdurahmanovic  
Hans Peter Rehm
  
feenschach 01-04/1989
 
[8/n1P5/2N1N3/Pp1PPk1P/8/4p3/K3B3/8]
  h#2(9+4)  
a) Diagram
b)-d) after the key of a)-c)

  7Fadil Abdurahmanovic  
 
feenschach, 1997
 
[3rkr2/7n/8/8/8/3p3B/7R/4K2R]
  h#2(4+5)  
a) Diagram
b) after the key

  8Christer Jonsson  
Michel Caillaud
  
StrateGems 10-12/2000
1st Prize
[8/3p4/8/1P4P1/p7/p1k1NN2/p1B5/rR4K1]
  h#2(7+6)  
a) Diagram
b)-d) after the key of a)-c)


  9Jaroslav Stun  
The Problemist 11/1988
 
[B4R2/2b1r1B1/4nN2/5P2/7R/prPkp3/bp6/1n3K2]
  h#2(8+10)  
a) Diagram
b) after the key

  10Anders Lundström  
feenschach 07-09/1986
3rd Prize, 43rd TT
[8/8/8/3p1pRP/K1BPp3/4Pk2/5B2/3n4]
  h#2*(7+5)  
a) Diagram
b) after the key

  11KCharles Mason Fox  
The Chess Amateur 08/1929
 
[8/8/8/3p1kn1/3pNp1R/3K4/8/7N]
  h#2(4+5)  
a) Diagram
b)after the key

Solutions
6a) 1. Ke4 c8=N 2. Kf5 Nd6#
b) 1. Kxd5 c8=B 2. Kxc6 Bf3#
c) 1. Kxe6 c8=R 2. Kd7 Bg4#
d) 1. Kf5 c8=Q+ 2. Kf4 Qg4#
Allumwandlung and round trip of the black king. This composition is an ímproved version of a 1st Prize by Abdurahmanovic which was published in feenschach 08/1985.
7a) 1. Rh8 0-0 2. d2 Re2#
b) 1. 0-0 Be6+ 2. Kh8 Rxh7#
Two remarkable things about a): Both black rook and white king have to step aside. Even the passive black knight is of thematic relevance. Solution b) is rather unspectacular.
8a) 1. d5 Nd2 2. d4 Ne4#
b) 1. d4 Bb3 2. d3 Nd5#
c) 1. d3 Nd4 2. d2 Ne2#
d) 1. d2 Bxa4 2. d1=N Rb3#
Impressing — Black moves are only done by the pawn!
9a) 1. Nf4 Nd5 2. Ke4 Nb4#
b) 1. Nd5 Ng4 2. Ke4 Ne5#
Self-pins and batteries.
10a) *1. - Bh4 2. Nf2 Rg3#
1. Nxe3 Bf1 2. Ng4 Rxf5#
b) *1. - Bf1 2. Ng4 Rxf5#
1. Ng2 Be1 2. Nf4 Rg3#
Nice model mates.
11a) 1. Nf3 Rh5+ 2. Kg4 Nf6#
b) 1. Ne5+ Ke2 2. Kxe4 Ng3#
Though the black d-pawns are a little bit suspicious, it's still a small surprise that the checkmating knight of a) is captured in b). Model mate in a) and even ideal mate in b).

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