Power and Limits of Structural Display Rules

Abstract

What can (and cannot) be expressed by structural display rules? Given a display calculus, we present a systematic procedure for transforming axioms into structural rules. The conditions for the procedure are given in terms of (purely syntactic) abstract properties of the base calculus; thus, the method applies to large classes of calculi and logics. If the calculus satisfies certain additional properties, we prove the converse direction, thus characterising the class of axioms that can be captured by structural display rules. Determining if an axiom belongs to this class or not is shown to be decidable. Applied to the display calculus for tense logic, we obtain a new proof of Kracht’s Display Theorem I.