Algebraic logic constitutes a vibrant interdisciplinary field that investigates the close interplay between algebraic structures and logical systems. By utilising tools from universal algebra, ...

Girard introduced phase semantics as a complete set-theoretic semantics of linear logic, and Okada modified phase-semantic completeness proofs to obtain normalform theorems. On the basis of these ...

In this paper we consider an intuitionistic variant of the modal logic S4 (which we call IS4). The novelty of this paper is that we place particular importance on the natural deduction formulation of ...