[Retros] Happy New Year!

[Francois Labelle]

To contrast with the New Year proof game composed by Noam, here are some 
computer generated ones.

Unfortunately the shortest possible examples are not "shortest" proof 
games:

rnbq1bnr/pppppkpp/5p2/8/8/2P1P3/PP1P1PPP/RNBQKBNR
2 solutions in 2.0 moves. How many solutions in 4.0 moves?

rnbq1b1r/ppppkppp/5n2/4Q3/4P3/8/PPPP1PPP/RNB1KBNR
(checkmate) 48 solutions in 3.5 moves. How many solutions in 4.5 moves?

rnbqkbnr/pppppppp/8/8/8/1N1P4/PPPQPPPP/RNB1KB1R
(one-sided) 12 solutions in 5 moves. How many solutions in 7 moves?

rnbqkbnr/pppppBpp/8/2P5/3P4/1Q2P3/PP3PPP/RNB1K1NR
(one-sided checkmate) 66 solutions in 7 moves. How many solutions in 8 
moves?

Here are some examples that are SPGs (are they better?):

rnbqkbnr/pppppppp/8/8/3P4/Q1PBP3/PP1N1PPP/RNB1K2R
OSPG in 8 moves. How many solutions?

rnbqkbnr/pppppBpp/8/6N1/1Q2P3/8/PPPP1PPP/RNB2RK1
Checkmate OSPG in 9 moves. How many solutions?

And a tough one:

2R5/5k2/8/8/8/8/2K5/8
Massacre SPG in 16.5 moves. How many solutions?

Here are the diagrams for the above problems:
  _________________ _________________ _________________ _________________

|                 |                 |                 |                 |

| r n b q . b n r | r n b q . b . r | r n b q k b n r | r n b q k b n r |

| p p p p p k p p | p p p p k p p p | p p p p p p p p | p p p p p B p p |

| . . . . . p . . | . . . . . n . . | . . . . . . . . | . . . . . . . . |

| . . . . . . . . | . . . . Q . . . | . . . . . . . . | . . P . . . . . |

| . . . . . . . . | . . . . P . . . | . . . . . . . . | . . . P . . . . |

| . . P . P . . . | . . . . . . . . | . N . P . . . . | . Q . . P . . . |

| P P . P . P P P | P P P P . P P P | P P P Q P P P P | P P . . . P P P |

| R N B Q K B N R | R N B . K B N R | R N B . K B . R | R N B . K . N R |

|_________________|_________________|_________________|_________________|

|                 |                 |                 |

| r n b q k b n r | r n b q k b n r | . . R . . . . . |

| p p p p p p p p | p p p p p B p p | . . . . . k . . |

| . . . . . . . . | . . . . . . . . | . . . . . . . . |

| . . . . . . . . | . . . . . . N . | . . . . . . . . |

| . . . P . . . . | . Q . . P . . . | . . . . . . . . |

| Q . P B P . . . | . . . . . . . . | . . . . . . . . |

| P P . N . P P P | P P P P . P P P | . . K . . . . . |

| R N B . K . . R | R N B . . R K . | . . . . . . . . |

|_________________|_________________|_________________|



CHESSBASE CHRISTMAS PROOF GAMES

ChessBase is hosting its annual Christmas chess puzzle series, and this 
year the theme is "proof games". People on the Retro list will find the 
problems easy and maybe already know all of them, but it's nice to see a 
gentle introduction to proof games for normal chess players.

http://www.chessbase.com/puzzle/christmas2004/index.htm

There will be a contest with prizes posted on January 1st, which is why 
some of the problems are without attribution.

 	Francois