Superrational types
  We present a formal analysis of Douglas Hofstadter's concept of
\emph{superrationality}. We start by defining superrationally justifiable
actions, and study them in symmetric games. We then model the beliefs of the
players, in a way that leads them to different choices than the usual
assumption of rationality by restricting the range of conceivable choices.
These beliefs are captured in the formal notion of \emph{type} drawn from
epistemic game theory. The theory of coalgebras is used to frame type spaces
and to account for the existence of some of them. We find conditions that
guarantee superrational outcomes.
