You can always compute maximally permissive controllers under partial observation when they exist

The maximal permissivity property of controllers is an optimal criterion that is often taken for granted as the result of synthesis algorithms; the algorithms are designed for frameworks where the existence and the uniqueness of a maximal permissive controller is demonstrated apart, as it fulfills sufficient hypotheses; these algorithms precisely compute this object. Still, maximally permissive solutions might exist in circumstances which do not fall into such identified frameworks, but there is no way to ensure that the algorithms deliver an optimal solution. In this paper, we propose a general synthesis procedure which always computes a maximal permissive controller when it exists.