1. Joined
    25 Aug '06
    Moves
    0
    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
    AGW Hitman
    http://xkcd.com/386/
    Joined
    23 Feb '07
    Moves
    7113
    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
    31 May '07
    Moves
    696
    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. Standard memberAThousandYoung
    or different places
    tinyurl.com/2tp8tyx8
    Joined
    23 Aug '04
    Moves
    26660
    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
    Ceres
    Joined
    14 Oct '06
    Moves
    18375
    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
    31 May '07
    Moves
    696
    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
    AGW Hitman
    http://xkcd.com/386/
    Joined
    23 Feb '07
    Moves
    7113
    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
    AGW Hitman
    http://xkcd.com/386/
    Joined
    23 Feb '07
    Moves
    7113
    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
    31 May '07
    Moves
    696
    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
    AGW Hitman
    http://xkcd.com/386/
    Joined
    23 Feb '07
    Moves
    7113
    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
    Joined
    11 Apr '07
    Moves
    92274
    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
    07 Sep '05
    Moves
    35068
    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
    02 Oct '07
    Moves
    5330
    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
    2014.05.01
    Joined
    11 Apr '07
    Moves
    92274
    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
    25 Aug '06
    Moves
    0
    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.
Back to Top

Cookies help us deliver our Services. By using our Services or clicking I agree, you agree to our use of cookies. Learn More.I Agree