 The term “stit” is an acronym based on “sees to it that”. The idea is to add, to an ordinary classical propositional language, a new propositional operator \(\stit\), interpreting \(\stit_i\phi\), where \(i\) stands for an agent and \(\phi\) for a proposition, as \(i\) sees to it that \(\phi\). (The official notation of the Belnap school is more laborious: [\(i \mathop{\mathsf{stit:}} \phi\)].) Note that \(\phi\) is allowed to contain nestings of the new operator.