In this paper, we develop a framework for obtaining completeness results for extensions of modal logics. A modal language is extended by fresh modalities, which are then specified using definitions formulated in the original logic. When adding the modal definitions to the axiom system, completeness of the extended logic is guaranteed by the main result of the paper. We demonstrate the technique by applying it to extensions of the modal logic S5.
Author(s)
Uridia, Levan
Razmadze Institute of Mathematics Tbilisi, Georgia
