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  1. Standard member SwissGambit
    Caninus Interruptus
    01 Oct '13 02:56
    R. Smullyan, 1981


    The white King has disguised himself as another piece (or pawn) of indeterminate color. Where is he?
  2. Subscriber Ponderableonline
    chemist
    01 Oct '13 05:15
    Originally posted by SwissGambit
    R. Smullyan, 1981
    [fen]qn2b1Qk/pPpNpP1p/p1P3P1/rp1R3P/P1N1P1B1/8/8/8 w - - 0 1[/fen]

    The white King has disguised himself as another piece (or pawn) of indeterminate color. Where is he?
    since the position is a checkmate and there is no legal way that the white Queen had come to that position without a previous checkmate, but the Queen can`t be the white King since then the position would be illegal I think the white King is the black King who in turn is disguised.
  3. Standard member wolfgang59
    Infidel
    01 Oct '13 05:17 / 2 edits
    Originally posted by SwissGambit
    R. Smullyan, 1981
    [fen]qn2b1Qk/pPpNpP1p/p1P3P1/rp1R3P/P1N1P1B1/8/8/8 w - - 0 1[/fen]

    The white King has disguised himself as another piece (or pawn) of indeterminate color. Where is he?
    The black king is checked so white had last move.
    Last move must have been Qg8 (not possible) or g8=Q (not possible)
    therefore the black king is an imposter and is really the white king

    but that's too easy!!!!

    Are you sure board is correct SG?

    edit: my typing is so slow!

    edit2: Of course white's last move was a capture on g8
  4. Standard member SwissGambit
    Caninus Interruptus
    01 Oct '13 05:20
    Originally posted by wolfgang59
    The black king is checked so white had last move.
    Last move must have been Qg8 (not possible) or g8=Q (not possible)
    therefore the black king is an imposter and is really the white king

    but that's too easy!!!!

    Are you sure board is correct SG?

    edit: my typing is so slow!
    Positions without both Kings aren't legal! So that's not it...
  5. 01 Oct '13 05:35
    Originally posted by SwissGambit
    Positions without both Kings aren't legal! So that's not it...
    The white king is disguised as....
    the black rook
  6. Standard member SwissGambit
    Caninus Interruptus
    01 Oct '13 06:42
    Originally posted by MISTER CHESS
    The white king is disguised as.... [hidden]the black rook[/hidden]
    Why that piece in particular?
  7. 01 Oct '13 08:57 / 1 edit
    I have a partial solution: The white king is not disguised as a white piece nor pawn.

    Explanation: (EDIT: the hiding doesn't work, so don't read what's coming if you want to solve it yourself)

    [hidden]
    Short summary:
    - a4, b7, Nc4, c6, Nd7, f7, g6 are all covered by black pieces
    - Qg8 is next to black's king
    - Rd5, e4, Bg4 and h5 still need explanation, see below.

    The latter are ruled out by tracing back what happened:
    - The game ended in checkmate with Qxg8#.
    - The queen could only come from f8, because from g7 the black king is already in check before white's move. So Qf8xg8# is the last move.
    - Black's last move must have been a piece move to g8 to block the queen check from f8. This move could only have been a knight move from f6 or h6. Why not a rook or queen move from g7? See later.
    - Where did the white queen come from before she checked on f8+? The only possibility is h6, otherwise the position is a check before white's move. This rules out the queen or rook move from g7, but more importantly, also the knight move from h6. The knight cannot suddenly appear on h6 once the queen moves Qh6f8+. So black's last move was Nf6g8.
    - Since black's knight was on f6: Rd5, e4, Bg4 and h5 can't be the white king, because they were attacked by the knight.

    As a result, the white king is not disguised as a white piece or pawn.
    [/hidden]
  8. 01 Oct '13 09:11
    Next step in the solution:

    The white king is disguised as the black pawn on c7.

    SPOILER ALERT!

    Explanation:

    Assuming all black's pawns are genuine, the following moves must have happened at some time during the game: b7xa6, d7xc6 and c6xb5. On the other hand, white has only lost 3 pieces: 1 pawn, the dark-squared bishop and 1 rook. Each of the captures by black's pawns thus corresponds to one of these white pieces.

    However, white's dark-squared bishop can only be captured on a dark square, and all captures by the black pawns have happened on light squares. So the initial assumption is wrong.

    Since all of the involved black pawns are attacked by black pieces, except for c7, c7 must be the white king. The black pawn on b5 then originally came from c7 by capturing the dark-squared bishop on b6 and then moving one step forward to b5.
  9. Standard member SwissGambit
    Caninus Interruptus
    01 Oct '13 13:12
    Originally posted by tvochess
    Next step in the solution:

    The white king is disguised as the black pawn on c7.

    SPOILER ALERT!

    Explanation:

    Assuming all black's pawns are genuine, the following moves must have happened at some time during the game: b7xa6, d7xc6 and c6xb5. On the other hand, white has only lost 3 pieces: 1 pawn, the dark-squared bishop and 1 rook. Each of the c ...[text shortened]... came from c7 by capturing the dark-squared bishop on b6 and then moving one step forward to b5.
    Well done. wK is on c7 because that reduces the number of black pawn captures by one. We don't know for sure that Bc1 was captured on b6 (it could also have been the promoted d-pawn).
  10. 01 Oct '13 14:15
    hey SwissGambit,

    I'm happy that my solution was correct. However, I don't understand your last comment. If Bc1 wasn't captured on b6, where else was it captured? I'm unsure, but do you mean that this bishop may have been captured by something else than a pawn?

    By the way, nice puzzle!
  11. Standard member SwissGambit
    Caninus Interruptus
    01 Oct '13 14:19
    Originally posted by tvochess
    hey SwissGambit,

    I'm happy that my solution was correct. However, I don't understand your last comment. If Bc1 wasn't captured on b6, where else was it captured? I'm unsure, but do you mean that this bishop may have been captured by something else than a pawn?

    By the way, nice puzzle!
    Yes, that's what I mean. Bc1 can be captured by something else.

    I like the problem too. I'm going through Smullyan's book Arabian Knights and this one stood out.
  12. 01 Oct '13 14:19
    Well done, I guess thats what I get for being lazy. I realized quickly that it was either the rook or the c7 pawn and that blacks pawns were fishy but used a logical fallacy that you can't prove the rook isn't the king, which of course is wrong because you can easily prove it by showing how the c7 pawn is actually the king. Again, well done.