Flagg and Friedman's Translation Is Not Faithful

Abstract

We prove that Flagg and Friedman's translation from epistemic to intuitionistic predicate (propositional) logics is not faithful.MSC: 03B20, 03B45, 03F99. Key words: Epistemic logic, intuitionistic logic, modal logic. In this note we show that the translation (.)y) proposed in [l] is not faithful, i.e. that the converse of Theorem 2.4 in [l] does not hold. A counterexample for the fact is p 3 Op' for p atomic. With the same counterexample, the converse of the propositional case of Theorem 2.4, i.e. Theorem 1.9 in [l] does not hold either. By making use of the translation, FLAGG and FRIEDMAN [l] gave a uniform treat-