Ontology-free modal semantics (Q1815412)

Believing that modal semantics should be done without ontological assumptions made by possible-worlds semantics the author reproduces Christopher Menzel's model-theoretical semantics for modal languages which works without assuming ``possibilia'', and builds up a more extensionalist ``ontology-free'' modification of it. Theorems 1 and 2 are proved in the Appendix getting irrationally the names ``Theorem 3'' and ``Theorem 4''.