% Francois Labelle & computer, February 25, 2012
% All 13 PG-5.0 SPG-2.5 with exactly 1 solution in 5.0 moves.
% They all have:
% - 1 solution in 2.5 moves
% - 0 solutions in 3.0 moves
% - 0 solutions in 3.5 moves
% - >200 solutions in 4.0 moves
% - >2000 solutions in 4.5 moves
% - 1 solution in 5.0 moves.

% Comment:
%
% The problem rnbqkb1r/ppBppppp/8/3n4/3P4/8/PPP1PPPP/RN1QKBNR
% was used in the Messigny 2011 retro solving competition. See
% http://www.pairlist.net/pipermail/retros/2011-June/003569.html
% http://www.phenix-echecs.fr/Messigny/Messigny_2011.pdf [French]
% (diagram on page 19 #1, solution on page 37).


(Forsyth-Edwards Notation, followed by the same list in ascii diagrams)

PG-5.0, SPG-2.5:

1nbqkbnr/rpBppppp/p7/8/3P4/8/PPP1PPPP/RN1QKBNR
1rbqkbnr/ppBppppp/2n5/8/3P4/8/PPP1PPPP/RN1QKBNR
1rbqkbnr/ppBppppp/n7/8/3P4/8/PPP1PPPP/RN1QKBNR
r1bqkbnr/ppBppppp/8/2n5/3P4/8/PPP1PPPP/RN1QKBNR
r1bqkbnr/ppBppppp/8/n7/3P4/8/PPP1PPPP/RN1QKBNR
rnbq1bnr/ppBppkpp/5p2/8/3P4/8/PPP1PPPP/RN1QKBNR
rnbqkb1r/ppBppppp/8/3n4/3P4/8/PPP1PPPP/RN1QKBNR
rnbqkb1r/ppBppppp/8/5n2/3P4/8/PPP1PPPP/RN1QKBNR
rnbqkb1r/ppBppppp/8/7n/3P4/8/PPP1PPPP/RN1QKBNR
rnbqkb1r/ppBppppp/8/8/3Pn3/8/PPP1PPPP/RN1QKBNR
rnbqkbn1/ppBppppr/7p/8/3P4/8/PPP1PPPP/RN1QKBNR
rnbqkbr1/ppBppppp/5n2/8/3P4/8/PPP1PPPP/RN1QKBNR
rnbqkbr1/ppBppppp/7n/8/3P4/8/PPP1PPPP/RN1QKBNR

 _________________ _________________ _________________ _________________ 
|                 |                 |                 |                 |
| . n b q k b n r | . r b q k b n r | . r b q k b n r | r . b q k b n r |
| r p B p p p p p | p p B p p p p p | p p B p p p p p | p p B p p p p p |
| p . . . . . . . | . . n . . . . . | n . . . . . . . | . . . . . . . . |
| . . . . . . . . | . . . . . . . . | . . . . . . . . | . . n . . . . . |
| . . . P . . . . | . . . P . . . . | . . . P . . . . | . . . P . . . . |
| . . . . . . . . | . . . . . . . . | . . . . . . . . | . . . . . . . . |
| P P P . P P P P | P P P . P P P P | P P P . P P P P | P P P . P P P P |
| R N . Q K B N R | R N . Q K B N R | R N . Q K B N R | R N . Q K B N R |
|_________________|_________________|_________________|_________________|
|                 |                 |                 |                 |
| r . b q k b n r | r n b q . b n r | r n b q k b . r | r n b q k b . r |
| p p B p p p p p | p p B p p k p p | p p B p p p p p | p p B p p p p p |
| . . . . . . . . | . . . . . p . . | . . . . . . . . | . . . . . . . . |
| n . . . . . . . | . . . . . . . . | . . . n . . . . | . . . . . n . . |
| . . . P . . . . | . . . P . . . . | . . . P . . . . | . . . P . . . . |
| . . . . . . . . | . . . . . . . . | . . . . . . . . | . . . . . . . . |
| P P P . P P P P | P P P . P P P P | P P P . P P P P | P P P . P P P P |
| R N . Q K B N R | R N . Q K B N R | R N . Q K B N R | R N . Q K B N R |
|_________________|_________________|_________________|_________________|
|                 |                 |                 |                 |
| r n b q k b . r | r n b q k b . r | r n b q k b n . | r n b q k b r . |
| p p B p p p p p | p p B p p p p p | p p B p p p p r | p p B p p p p p |
| . . . . . . . . | . . . . . . . . | . . . . . . . p | . . . . . n . . |
| . . . . . . . n | . . . . . . . . | . . . . . . . . | . . . . . . . . |
| . . . P . . . . | . . . P n . . . | . . . P . . . . | . . . P . . . . |
| . . . . . . . . | . . . . . . . . | . . . . . . . . | . . . . . . . . |
| P P P . P P P P | P P P . P P P P | P P P . P P P P | P P P . P P P P |
| R N . Q K B N R | R N . Q K B N R | R N . Q K B N R | R N . Q K B N R |
|_________________|_________________|_________________|_________________|
|                 |
| r n b q k b r . |
| p p B p p p p p |
| . . . . . . . n |
| . . . . . . . . |
| . . . P . . . . |
| . . . . . . . . |
| P P P . P P P P |
| R N . Q K B N R |
|_________________|