Posers and Puzzles

Posers and Puzzles

  1. Joined
    24 Jan '07
    Moves
    7582
    16 Jun '07 13:28
    It is common in chess for a player to have only one legal move.

    Occasionally, as in the position below, there will be a forced sequence of two half-moves, i.e. only one legal move and only one legal reply.



    Black must play Rxh7+, white must reply Bxh7. Neither has any other choice (except resignation etc).

    What is the longest forced sequence you can create? N.B. moves must be only legal moves, for both sides.
  2. Joined
    31 May '07
    Moves
    696
    16 Jun '07 14:18
    You're going to get some pretty horrible positions. Best I could get, in all of 1 minute thinking, was this:
    15 forced half moves.

  3. Joined
    09 Jun '07
    Moves
    1416
    16 Jun '07 15:272 edits

    3 half moves. (Black first)
  4. Joined
    24 Jan '07
    Moves
    7582
    16 Jun '07 15:36
    Originally posted by DeepRed
    [fen]K7/3p4/2pP4/k1P5/Pp6/1P6/8/8[/fen]
    3 half moves. (Black first)
    Are you sure? Black's 1st move is forced - Ka6 but then white has a choice of either Kb8 or a5, doesn't he?
  5. Joined
    09 Jun '07
    Moves
    1416
    16 Jun '07 15:45
    Originally posted by d36366
    Are you sure? Black's 1st move is forced - Ka6 but then white has a choice of either Kb8 or a5, doesn't he?
    True.
  6. Standard memberSwissGambit
    Caninus Interruptus
    2014.05.01
    Joined
    11 Apr '07
    Moves
    92274
    16 Jun '07 21:321 edit
    Originally posted by doodinthemood
    You're going to get some pretty horrible positions. Best I could get, in all of 1 minute thinking, was this:
    15 forced half moves.
    After considerably more than one minute of thought, I was able to eke out an extra half-ply:


    next 16 ply are forced
  7. Joined
    31 May '07
    Moves
    696
    17 Jun '07 11:151 edit

    Sadly illegal, but more attractive than my last one when you play it through.
    Still only 15 half moves. Ends in checkmate.
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