Free μ-lattices

A μ-lattice is a lattice with the property that every unary polynomial has both a least and a greatest fix-point. In this paper we define the quasivariety of μ-lattices and, for a given partially ordered set P, we construct a μ-lattice image whose elements are equivalence classes of games in a preordered class image. We prove that the μ-lattice image is free over the ordered set P and that the order relation of image is decidable if the order relation of P is decidable. By means of this characterization of free μ-lattices we infer that the class of complete lattices generates the quasivariety of μ-lattices.