% Francois Labelle & computer, January 24, 2004 % All 12 at home PG-4.0 with exactly 2 solutions. % They are all SPGs. % Comment by Joost de Heer (January 28, 2004): % % Only one acceptable double-solution proofgame in 8 halfmoves: % % rnbqkbnr/pp1ppppp/8/8/8/8/PPP1PPPP/RN1QKBNR % SPG 4.0 (2 solutions) % % 1. d4 Nc6 2. Bf4 Nd4 3. Bc7 Nc6 4. Bb8 Nb8 % 1. d4 c5 2. Bh6 cd4 3. Qd4 Nh6 4. Qd1 Ng8 % % These two solutions are distinct enough to be acceptable. A pity is % the repeated first move. % Comment: % % This "acceptable double-solution proofgame" was discovered before % by Cornel Pacurar (see http://anselan.com/CHEB.html). (Forsyth-Edwards Notation, followed by the same list in ascii diagrams) SPG-4.0: rnbqkbn1/ppp2ppp/8/8/8/8/PPPPPPPP/R1BQKBNR rnb1kbnr/ppppp1pp/8/8/8/8/PPPPPPPP/R1BQKBNR rnbqkbnr/pppp1ppp/8/8/8/8/PPP1PPPP/R1BQKBNR rnbqkbnr/pppp1ppp/8/8/8/8/1PP1PPPP/RNBQKBNR 1nbqkbnr/ppp2ppp/8/8/8/8/PPPPPPPP/RNBQKB1R rn1qkbnr/ppp1pppp/8/8/8/8/PPPP1PPP/RNBQKBNR r1bqkbnr/ppp1pppp/8/8/8/8/PPPP1PPP/RNBQKBNR rnbqkbnr/ppp1ppp1/8/8/8/8/PPPP1PPP/RNBQKBNR rnbqkbnr/1pp1pppp/8/8/8/8/PPPP1PPP/RNBQKBNR rnbqkbnr/pppp1ppp/8/8/8/8/PPP1PPP1/RNBQKBNR rnbqkbnr/pppp1ppp/8/8/8/8/PPP1PPPP/RN1QKBNR rnbqkbnr/pp1ppppp/8/8/8/8/PPP1PPPP/RN1QKBNR _________________ _________________ _________________ _________________ | | | | | | r n b q k b n . | r n b . k b n r | r n b q k b n r | r n b q k b n r | | 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 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 . B Q K B N R | R . B Q K B N R | R . B Q K B N R | R N B Q K B N R | |_________________|_________________|_________________|_________________| | | | | | | . n b q k b n r | r n . q k b n r | r . b q k b n r | r n b q k b n r | | 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 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 B Q K B . R | R N B Q K B N R | R N B Q K B N R | R N B Q K B N R | |_________________|_________________|_________________|_________________| | | | | | | r n b q k b n r | r n b q k b n r | r n b q k b n r | r n b q k b n r | | . 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 P P | P P P . P P P . | P P P . P P P P | P P P . P P P P | | R N B Q K B N R | R N B Q K B N R | R N . Q K B N R | R N . Q K B N R | |_________________|_________________|_________________|_________________|