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  • Players: Black and White.

  • A crosscut is a 2x2 subgrid with two white and two black stones, in which like-colored stones are diagonally adjacent (and opposite-colored stones are orthogonally adjacent).

  • To swap is to exchange locations of two stones.

  • Start: Fill the squares on a 8x8 grid with any configuration of 32 white stones and 32 black stones.

  • Play: Each turn, the player selects a piece of their color in a crosscut. The player swaps the selected piece with different opponent stones sharing a crosscut with it, until it is no longer in a crosscut. During this process, each swapped enemy stone must be different.

  • Goal: If, at any time during your turn or your opponent's turn, there is an orthogonal path of stones connecting your goal edges (for Black it is North-South, for White it is East-West), you win.

There are cooperative cycles in this game, which seem to always arise from a single 3x3 pattern. However, for every one of those known cooperative cycles on the 5x5 grid, continuing the cycle appears to be a game-losing mistake. Therefore, I am interested in whether forced cycles might exist (a situation in which it is in both players interest to continue the cycle).

I think I have narrowed it down to the idea that a forced cycle, if it existed, must happen because one corner of the 3x3 cyclic template would somehow be important for making a winning connection. However, no matter which way I try, it is always possible for players to make a winning connection without using that corner.

However, multiple of these 3x3 cyclic templates could fit on a board, complicating the issue.

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    There's been various questions here about (cooperative) cycles in cross-cutting board games, like this question and this one. Are these all coming from somewhere particular? – xnor Aug 31 '23 at 03:22
  • For anyone curious about such 3x3 shapes, OP may have in mind the pattern with 3-4-5-8 black, and 1-2-6-7-9 white (numbered top to bottom, left to right). Assuming no surrounding interference (OP's rules make it sound like you cannot choose to prematurely end a swap sequence while your stone remains in a crosscut), then this can cooperatively cycle to and from the shape consisting of 3-4-8-9 black and 1-2-5-6-7 white. – Feryll Aug 31 '23 at 05:27

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