Stalnaker's Epistemic Logic by Laura P. Gamboa Guzman This work is a formalization of Stalnaker's epistemic logic with countably many agents and its soundness and completeness theorems, as well as the equivalence between the axiomatization of S4 available in the Epistemic Logic theory and the topological one. It builds on the Epistemic Logic theory. https://www.isa-afp.org/entries/Stalnaker_Logic.html