An Approximation Semantics for the Propositional Mu-Calculus

We give a new semantics for the propositional μ-calculus, prove that it is equivalent to the standard semantics and use it in order to propose a constraint based axiomatization of the μ-calculus. We show that our axiomatization is sound relatively to our semantics. Completeness of the system is the topic of ongoing research but we give a simple example of how our system could be used to construct a finite counter-example of an unprovable sentence.