1. Joined
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    22 Nov '07 16:56
    Can you find a symmetric position (there is a black piece on file X rank Y if and only if there is an equal white piece on file X rank 9-Y) in which it's white's turn and black wins?

    Try doing it with minimal number of pieces...
  2. Standard memberagryson
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    22 Nov '07 17:171 edit
    Originally posted by David113
    Can you find a symmetric position (there is a black piece on file X rank Y if and only if there is an equal white piece on file X rank 9-Y) in which it's white's turn and black wins?

    Try doing it with minimal number of pieces...
    6 pieces,
    White: King at A1, Rooks at B5 and B6
    Black: King at A8, Rooks at B4 and B3

    White moves any rook to A File, Checkmate.

    Sorry, Dunno how to insert boards.
  3. Joined
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    22 Nov '07 17:22


    There will be much better positions than that, but that's a mate in 4 for black whatever white does.
  4. SubscriberAThousandYoung
    All My Soldiers...
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    22 Nov '07 17:22
    Originally posted by David113
    Can you find a symmetric position (there is a black piece on file X rank Y if and only if there is an equal white piece on file X rank 9-Y) in which it's white's turn and black wins?

    Try doing it with minimal number of pieces...
    It can be done with one King and one Pawn each. Simple opposition endgame. Unfortunately I'm not sure what the exact position would be as I never looked into it very carefully.
  5. Standard memberadam warlock
    Baby Gauss
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    22 Nov '07 17:22
    Originally posted by agryson
    8 pieces,
    White: King at A1, Rooks at G6 and H7, pawn at G4
    Black: King at A8, Rooks at G3 and H2, pawn at G4

    White moves G6 Rook to G8, Checkmate.

    Sorry, Dunno how to insert boards.
    If you got winboard just put there the position you want. The go to file and choose copy position to clipboard. The when you are posting click on the Insert board from FEN link and paste the text on the window that appears.
    I think you can do that too with any other game viewer software.
  6. Joined
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    22 Nov '07 17:26
    * thousandyoung, sadly not. If you think about it. with symmetry, it has to be a position where kings are on opposite coloured squares. Opposition for black is not an option.
  7. Standard memberagryson
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    22 Nov '07 18:20
    Originally posted by adam warlock
    If you got winboard just put there the position you want. The go to file and choose copy position to clipboard. The when you are posting click on the Insert board from FEN link and paste the text on the window that appears.
    I think you can do that too with any other game viewer software.
    Thanks, I'll get to googling viewing software...!
  8. Standard memberagryson
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    22 Nov '07 18:22
    Originally posted by doodinthemood
    * thousandyoung, sadly not. If you think about it. with symmetry, it has to be a position where kings are on opposite coloured squares. Opposition for black is not an option.
    Do you have a solution? Not to have it, but just to know the minimum number of pieces we can aim for...
  9. Joined
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    22 Nov '07 18:23
    My pathetic solution is shown above. 12 pieces, white moves, then black mates in 4. It gives people something to work under at least 🙂
  10. Standard memberagryson
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    22 Nov '07 18:382 edits
    Originally posted by agryson
    6 pieces,
    White: King at A1, Rooks at B5 and B6
    Black: King at A8, Rooks at B4 and B3

    White moves any rook to A File, Checkmate.

    Sorry, Dunno how to insert boards.


    Here's the game I posted earlier.

    Thanks again Adam.

    ... didn't read question, white to move, black to win... bugger, back in half an hour...
  11. Standard memberSwissGambit
    Caninus Interruptus
    2014.05.01
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    23 Nov '07 05:46
    Originally posted by David113
    Can you find a symmetric position (there is a black piece on file X rank Y if and only if there is an equal white piece on file X rank 9-Y) in which it's white's turn and black wins?

    Try doing it with minimal number of pieces...
    Beat this!


    White to move

    White is in zugzwang - he must give up a pawn for nothing, or commit his King and allow a winning pawn push [1.Kb2 d2, for example].
  12. Joined
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    23 Nov '07 15:12
    Originally posted by SwissGambit
    Beat this!

    [fen]2k5/8/1P1P4/8/8/1p1p4/8/2K5 w - - 0 1[/fen]
    White to move

    White is in zugzwang - he must give up a pawn for nothing, or commit his King and allow a winning pawn push [1.Kb2 d2, for example].
    Very nice!
  13. Joined
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    23 Nov '07 16:26
    Swissgambit, is your solution original or do you have a source? Do you think there's other minimal solutions? I don't think fewer pieces is possible.
  14. Standard memberSwissGambit
    Caninus Interruptus
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    23 Nov '07 21:21
    Originally posted by zzyw
    Swissgambit, is your solution original or do you have a source? Do you think there's other minimal solutions? I don't think fewer pieces is possible.
    I have a vague memory of seeing something like this before. I would not be surprised if this position is already known.

    There may be other solutions with 2 pawns each. Even the position I gave can be shifted right or left, so it's really not just one solution.
  15. Joined
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    24 Nov '07 20:43
    Originally posted by SwissGambit
    Beat this!

    [fen]2k5/8/1P1P4/8/8/1p1p4/8/2K5 w - - 0 1[/fen]
    White to move

    White is in zugzwang - he must give up a pawn for nothing, or commit his King and allow a winning pawn push [1.Kb2 d2, for example].
    This is the intended solution.
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