Free Modal Algebras: A Coalgebraic Perspective
In this paper we discuss a uniform method for constructing free modal and distributive modal algebras. This method draws on works by (Abramsky 2005) and (Ghilardi 1995).We revisit the theory of normal forms for modal logic and derive a normal form representation for positive modal logic. We also show that every finitely generated free modal and distributive modal algebra axiomatised by equations of rank 1 is a reduct of a temporal algebra.
Bezhanishvili N., Kurz A. (2007) Free Modal Algebras: A Coalgebraic Perspective. In: Mossakowski T., Montanari U., Haveraaen M. (eds) Algebra and Coalgebra in Computer Science. CALCO 2007. Lecture Notes in Computer Science, vol 4624. Springer, Berlin, Heidelberg