Full Models for Positive Modal Logic

The positive fragment of the local modal consequence relation defined by the class of all Kripke frames is studied in the context of Abstract Algebraic Logic. It is shown that this fragment is non‐protoalgebraic and that its class of canonically associated algebras according to the criteria set up in 7] is the class of positive modal algebras. Moreover its full models are characterized as the models of the Gentzen calculus introduced in 3].