public: String name()

    public: Any setup(Map mState s, Set<Tile>Bag<Tile> st)

    // the player is handed the inital map, which is visible to all,

    // plus an initial set of tiles;

    // The method is also called when the referee resumes a

    // game from a game state so that players are guaranteed

    // to know their assets.

    public: PASS or REPLACE or EXTENSION takeTurn(PublicState s)

    // after receiving the public part of state, a player

    // - passes,

    // - asks the referee to replace its set of tiles, or

    // - requests the extension of the map in the given state with

    //   some tile placements

    public Any newTiles(Set<Tile>Bag<Tile> st)

    // the player is handed a new set of tiles

    public: Any win(Boolean w)

    // the player is informed whether it won or not

    referee                         player (p_1) . . . player (p_n)

      |                                |                 |

      |                                |                 |

      |                                |                 |

      |     setup(state,bagOfTiles)    |                 | % the initial map for this game

      | -----------------------------> |                 | % a set of tiles for this player

      |                                |                 |

      .                                .                 .

      .                                .                 . % repeat for descending age

      .                                .                 .

      |                                |                 |

      |     setup(state,bagOfTiles)    |                 |

      | -----------------------------------------------> |

      |                                |                 |

    referee                         player (p_1) . . . player (p_n)

      |                                |                 |

      |   take-turn(PublicState)       |                 | % player receives:

      | -----------------------------> |                 | % - current visible state            

      ACTION 1:

      |     PASS                       |                 |

      | <============================  |                 | % pass on this turn

      |                                |                 |

      ACTION 2:

      |     REPLACE                    |                 |

      | <============================  |                 | % replace request

      |                                |                 |

      |--+                             |                 |

      .  |                             .                 . % if legal:

      .  |                             .                 . % completes turn

      .  |                             .                 . % otherwise:

      .<-+                             .                 . % kick player out

      ACTION 3:

      |     EXTENSION                  |                 | % an extension consists of a

      | <============================  |                 | - non-empty sequence of

      |                                |                 | - tile-coordinate pairs

      |--+                             |                 |

      .  |                             .                 . % if legal:

      .  |                             .                 . % referee modifies game state

      .  |                             .                 . % completes turn

      .  |                             .                 . % otherwise:

      .  |                             .                 . % kick player out

      .<-+                             .                 .

      IF: the player asks for REPLACE or EXTENSIONS, the referee completes the turn:

      |                                |                 |

      |     new-tiles(bagOfTiles)      |                 | % the player is handed

      | -----------------------------> |                 | % a new set of tiles

      REPEAT:

      |   take-turn(PublicState)       |                 |

      | -----------------------------------------------> |

      |     response                   |                 |

      | <=============================================== |

      |                                |                 |

      .                                .                 .

      .                                .                 . % repeat until the referee

      .                                .                 . % determines that the game is over

      .                                .                 .

    referee                        player (p_1) . . . player (p_n)

      |                                |                 |

      |                                |                 |

      |     win(Boolean)               |                 |

      | -----------------------------> |                 | % true means "winner"

      |                                |                 | % false means "loser"

      .                                .                 .

      .                                .                 .

      .                                .                 .

      .                                .                 .

      |     win(Boolean)               |                 |

      | -----------------------------------------------> | % both winners and

      |                                |                 | % losers are informed

      |                                |                 |

    ------> are calls

    <====== are returns