The main result of this paper is the following theorem: each modal logic extending K4 having the branching property below m and the effective m-drop point property is decidable with respect to ...

Modal logic, an extension of classical logic, investigates the modes of truth such as necessity and possibility. Its development has been closely intertwined with advances in proof theory, a field ...

Tradition states that above the entrance to Plato’s Academy were inscribed the words, “Let no one ignorant of geometry enter here.” A student in the modal logic interim course studies how subjunctives ...