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 ...

Studia Logica: An International Journal for Symbolic Logic, Vol. 49, No. 2 (1990), pp. 197-214 (18 pages) We illustrate, with three examples, the interaction between boolean and modal connectives by ...

This is a preview. Log in through your library . Abstract THINKER is an automated natural deduction first-order theorem proving program. This paper reports on how it was adapted so as to prove ...