[Retros] Consequent helpmate

[liskov at im.bas-net.by]

My article in StrateGems 50 is entitled "Consequent Helpmate: A New Modest
Kind of Fairy Retro". As Joost wrote, consequent helpmate (hc#) means that
"each position is evaluated independently from the history. So even if
a rook moved during the solution, it can castle." Of course, the existence of
a castling-right-preserving proofgame in the castling position is required
as always. Strangely enough, I had never met such a natural stipulation
(resembling ser-hc#) before. Of course, it can also be implemented without
retro, merely as a fairy helpmate.

The article contains 5 my original retros, all dealing with castling.
Here are two ones:

  VL (SG 50, 2010)
White Kh8 Bh2 Sb8
Black Kd8 Rc8 Pb7 Pe7 Ph7 Ph6
+---a---b---c---d---e---f---g---h---+

|                                   |

8   .   S  -R  -K   .   .   .   K   8

|                                   |

7   .  -P   .   .  -P   .   .  -P   7

|                                   |

6   .   .   .   .   .   .   .  -P   6

|                                   |

5   .   .   .   .   .   .   .   .   5

|                                   |

4   .   .   .   .   .   .   .   .   4

|                                   |

3   .   .   .   .   .   .   .   .   3

|                                   |

2   .   .   .   .   .   .   .   B   2

|                                   |

1   .   .   .   .   .   .   .   .   1

|                                   |

+---a---b---c---d---e---f---g---h---+
 hc#3                     (3 + 6)

1.Ke8 Sd7 2.Ra8 K*h7! 3.0-0-0! Sb6#.

  VL (SG 50, 2010)
White Kh4 Ra2 Ba7 Pb5
Black Ke8 Ra8 Rg5 Bg7 Pb7 Pc2 Pa5 Pd7 Pe6 Pf7 Pg6 Ph7
+---a---b---c---d---e---f---g---h---+

|                                   |

8  -R   .   .   .  -K   .   .   .   8

|                                   |

7   B  -P   .  -P   .  -P  -B  -P   7

|                                   |

6   .   .   .   .  -P   .  -P   .   6

|                                   |

5  -P   P   .   .   .   .  -R   .   5

|                                   |

4   .   .   .   .   .   .   .   K   4

|                                   |

3   .   .   .   .   .   .   .   .   3

|                                   |

2   R   .  -P   .   .   .   .   .   2

|                                   |

1   .   .   .   .   .   .   .   .   1

|                                   |

+---a---b---c---d---e---f---g---h---+
 hc#2    3.1.1.1          (4 + 12)

By now I composed also several hc#-retros with post-key e.p. captures
(a more formidable combination: in "memoryless" chess not merely the
corresponding double pawn's move should be made but this has to be
the only legal last move in the position). The first one is to be
published in StrateGems as well.

Valery Liskovets