final coalgebra of the 𝓟${_{<κ}}$(A×X) endo-functor in $Set^*$?












4












$begingroup$


In the paper Coalgebraic Games and Strategies F. Honsell, M. Lenisa, and R. Redamalla use the functor $F_A$(X) = ${mathscr{P}_{<κ}}$(A×X) to define games coalgebraically. This is a functor from the category of $Set^* to Set^*$ where $Set^*$ is the category of sets satisfying the antifoundation axioms.



They state that the final $F_A$ coalgebra is ($G_A$,id) and that a game is to be understood as an element of $G_A$, but I don't know where the final coalgebra construction for $F_A$ is explained in detail. Why would id be the coalgebraic function?



They write




The elements of the final coalgebra $G_A$ are the minimal graphs
up-to bisimilarity.




To add a bit more context as to how this relates to games:




We consider a general notion of 2-player game of perfect information,
where the two players are called Left (L) and Right (R). A game x is
identified with its initial position; at any position, there are moves
for L and R, taking to new positions of the game. By abstracting from
superficial features of positions, games can be viewed as elements of
the final coalgebra for the functor F$_A$(X) = $mathscr{P}_{<κ}$(A×X), where A is a
parametric set of atoms which encode information on moves and
positions, i.e. move names, and the player who has moved, and $mathscr{P}_{<κ}$ is
the set of all subsets of cardinality < κ. The coalgebra structure
captures, for any position, the moves of the players and the
corresponding next positions.




as for the meaning of $mathscr{P}_{<κ}$ this is explained in a later article "Multigames and strategies, coalgebraically"




$mathscr{P}_{<κ}$is the set of all subsets of cardinality < κ, where κ can be ω, if only finitely branching games are considered, or it can be an inaccessible cardinal, if we are interested in more general games.




PS I posted this question on mathoverflow yesterday, thinking I was on math.stackexchange...










share|cite|improve this question











$endgroup$

















    4












    $begingroup$


    In the paper Coalgebraic Games and Strategies F. Honsell, M. Lenisa, and R. Redamalla use the functor $F_A$(X) = ${mathscr{P}_{<κ}}$(A×X) to define games coalgebraically. This is a functor from the category of $Set^* to Set^*$ where $Set^*$ is the category of sets satisfying the antifoundation axioms.



    They state that the final $F_A$ coalgebra is ($G_A$,id) and that a game is to be understood as an element of $G_A$, but I don't know where the final coalgebra construction for $F_A$ is explained in detail. Why would id be the coalgebraic function?



    They write




    The elements of the final coalgebra $G_A$ are the minimal graphs
    up-to bisimilarity.




    To add a bit more context as to how this relates to games:




    We consider a general notion of 2-player game of perfect information,
    where the two players are called Left (L) and Right (R). A game x is
    identified with its initial position; at any position, there are moves
    for L and R, taking to new positions of the game. By abstracting from
    superficial features of positions, games can be viewed as elements of
    the final coalgebra for the functor F$_A$(X) = $mathscr{P}_{<κ}$(A×X), where A is a
    parametric set of atoms which encode information on moves and
    positions, i.e. move names, and the player who has moved, and $mathscr{P}_{<κ}$ is
    the set of all subsets of cardinality < κ. The coalgebra structure
    captures, for any position, the moves of the players and the
    corresponding next positions.




    as for the meaning of $mathscr{P}_{<κ}$ this is explained in a later article "Multigames and strategies, coalgebraically"




    $mathscr{P}_{<κ}$is the set of all subsets of cardinality < κ, where κ can be ω, if only finitely branching games are considered, or it can be an inaccessible cardinal, if we are interested in more general games.




    PS I posted this question on mathoverflow yesterday, thinking I was on math.stackexchange...










    share|cite|improve this question











    $endgroup$















      4












      4








      4





      $begingroup$


      In the paper Coalgebraic Games and Strategies F. Honsell, M. Lenisa, and R. Redamalla use the functor $F_A$(X) = ${mathscr{P}_{<κ}}$(A×X) to define games coalgebraically. This is a functor from the category of $Set^* to Set^*$ where $Set^*$ is the category of sets satisfying the antifoundation axioms.



      They state that the final $F_A$ coalgebra is ($G_A$,id) and that a game is to be understood as an element of $G_A$, but I don't know where the final coalgebra construction for $F_A$ is explained in detail. Why would id be the coalgebraic function?



      They write




      The elements of the final coalgebra $G_A$ are the minimal graphs
      up-to bisimilarity.




      To add a bit more context as to how this relates to games:




      We consider a general notion of 2-player game of perfect information,
      where the two players are called Left (L) and Right (R). A game x is
      identified with its initial position; at any position, there are moves
      for L and R, taking to new positions of the game. By abstracting from
      superficial features of positions, games can be viewed as elements of
      the final coalgebra for the functor F$_A$(X) = $mathscr{P}_{<κ}$(A×X), where A is a
      parametric set of atoms which encode information on moves and
      positions, i.e. move names, and the player who has moved, and $mathscr{P}_{<κ}$ is
      the set of all subsets of cardinality < κ. The coalgebra structure
      captures, for any position, the moves of the players and the
      corresponding next positions.




      as for the meaning of $mathscr{P}_{<κ}$ this is explained in a later article "Multigames and strategies, coalgebraically"




      $mathscr{P}_{<κ}$is the set of all subsets of cardinality < κ, where κ can be ω, if only finitely branching games are considered, or it can be an inaccessible cardinal, if we are interested in more general games.




      PS I posted this question on mathoverflow yesterday, thinking I was on math.stackexchange...










      share|cite|improve this question











      $endgroup$




      In the paper Coalgebraic Games and Strategies F. Honsell, M. Lenisa, and R. Redamalla use the functor $F_A$(X) = ${mathscr{P}_{<κ}}$(A×X) to define games coalgebraically. This is a functor from the category of $Set^* to Set^*$ where $Set^*$ is the category of sets satisfying the antifoundation axioms.



      They state that the final $F_A$ coalgebra is ($G_A$,id) and that a game is to be understood as an element of $G_A$, but I don't know where the final coalgebra construction for $F_A$ is explained in detail. Why would id be the coalgebraic function?



      They write




      The elements of the final coalgebra $G_A$ are the minimal graphs
      up-to bisimilarity.




      To add a bit more context as to how this relates to games:




      We consider a general notion of 2-player game of perfect information,
      where the two players are called Left (L) and Right (R). A game x is
      identified with its initial position; at any position, there are moves
      for L and R, taking to new positions of the game. By abstracting from
      superficial features of positions, games can be viewed as elements of
      the final coalgebra for the functor F$_A$(X) = $mathscr{P}_{<κ}$(A×X), where A is a
      parametric set of atoms which encode information on moves and
      positions, i.e. move names, and the player who has moved, and $mathscr{P}_{<κ}$ is
      the set of all subsets of cardinality < κ. The coalgebra structure
      captures, for any position, the moves of the players and the
      corresponding next positions.




      as for the meaning of $mathscr{P}_{<κ}$ this is explained in a later article "Multigames and strategies, coalgebraically"




      $mathscr{P}_{<κ}$is the set of all subsets of cardinality < κ, where κ can be ω, if only finitely branching games are considered, or it can be an inaccessible cardinal, if we are interested in more general games.




      PS I posted this question on mathoverflow yesterday, thinking I was on math.stackexchange...







      category-theory game-theory coalgebras






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      edited Jan 5 at 18:19







      Henry Story

















      asked Jan 5 at 17:43









      Henry StoryHenry Story

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