# 2000 seminar talk: Classical logic models

Talk held by Mladen Pavicic (University of Zagreb) at the KGRC seminar on 2000-11-17.

### Abstract

A well-known ortholattice model of classical propositional logic is the Boolean algebra (a distributive ortholattice, which is therefore orthomodular as well). In this talk I will show that there is also another ortholattice model of classical propositional logic which is neither distributive nor orthomodular so that classical propositional logic turns out to be non-categorical. I give the soundness and completeness proofs for the new model and compare them with those for the Boolean algebra.