Challenge 2
When can forward moves be proved legal or illegal by DR?
(Forward Castling and En Passant Under A1.3)
Note: for DR problems, we propose that all the regular retro conventions (concerning
who has the move, castling & e.p. rights, if these are not specified or deducible) are
simply switched off. As you will see there is quite enough complexity without them.
k1b5/1pPp4/pP1P4/P7/8/8/8/R3K3 w - - id #057 (6+5) DR. White to move. Last move?;
7k/6pP/6P1/3PpK2/1B2P3/8/8/8 w - - id #058 (6+3) DR. White to move. En passant OK?;
RBk5/KpPp4/bPpP4/1pP3Pp/1p5P/1P4p1/6P1/8 w - - id #059 DR. (11+9) White to move.
Last move? En passant OK?;
RBk5/KpPp4/bPpP4/1pP2Pp1/1p4P1/1P3p2/5P2/8 w - - id #059a (11+9) Whose
move?; [A variant on #059: the 5-pawn "question-mark"-shaped cluster is shifted one
file.]
8/8/8/8/5P2/4PpPp/PP1PpPpp/R1B1K1kr w - - id #060 (10+7) DR. White to move. Last
move? Castling rights?;
k1b5/1pPp4/1P1P4/1P5p/5P1P/5PNR/3NPBBQ/4K2R w - - id #061 (16+5) DR. White to move. Castling rights?;
8/1R2p1pB/4P1p1/R1PpKpP1/1PkBpP2/2P1P3/2P5/8 w - - id #062 (13+7) DR. White to
move. Last move? En passant OK?;
KBb1kb1r/PpPppppp/8/p7/8/8/8/8 w - - id #063 (4+11) DR. White to move. Last move?
Castling rights?;
8/8/8/8/QB2P1P1/pPRP1p2/PpP2P2/brk1KR1R w - - id #066a (13+6) White to move. Castling rights?; From an problem-solving perspective, much more interesting is the non-DR restricted position, #066, which differs only in the location of the White bishop: 7B/8/8/8/Q3P1P1/pPRP1p2/PpP2P2/brk1KR1R w - - id #066 (13+6) DR. White to move. Castling rights?;
2b1krbr/1pPp1p1n/3P1P1P/5PpK/6P1/8/8/8 w - - id #067 (7+10) DR. White to move. Last
move? En passant OK? Castling rights?;
B5b1/5pBb/p4Pp1/P5P1/8/1PPPkNPN/Q1P5/R3K2R w - - id #068 (15+6) DR. White to
move. Last move? Castling rights?;
3rk2r/b1p1p3/3pp2p/2ppKp2/4bP2/2n5/8/1q6 w - - id #070 (2+15) DR. Noam Elkies. Castling rights?;
r3k3/1b1p1p1p/2p2P1P/p4PKR/5PRQ/p4pPN/P4P1B/6B1 w - - id #072 (14+10) DR. Noam Elkies version by Andrew Buchanan. White to move. Last move? Castling rights?;
8/5PQ1/6P1/4B1P1/3P1PP1/4kP1N/B3P3/RN2K2R w - - id #082 (16+1) DR. Mate in 3. Castling rights?;
Here are two older ones, which fit into the scheme:
8/8/4P1Q1/5B2/5PP1/1PP1kNP1/6P1/R3K2N w - - id #041 (13+1) DR. Mate in 2.;
5b1k/p1p1p1pP/P1P1P1P1/KpP4p/8/7P/1P6/8 w - - id #042 (9+8) DR. White to move.
Last move? Can White mate in 6? If Pb2 is on b3, and Ph3 is on h2, what then?;
Summary Table:
Type of move Position Move Problem #
living/dead? legal/illegal?
----------------------------------------------------------
En Passant Living Legal #042, #062, #067
En Passant Living Illegal #062 again
En Passant Dead Legal #058
En Passant Dead Illegal #059
White Castling Living Legal #041, #044, #068
White Castling Living Illegal #082
White Castling Dead Legal #061
White Castling Dead Illegal #060, #066a
Black Castling Living Legal #070
Black Castling Living Illegal #067 again
Black Castling Dead Legal #072
Black Castling Dead Illegal #063
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