From $μ$-Calculus to Alternating Tree Automata using Parity Games

Abstract: $\mu$-Calculus and automata on infinite trees are complementary ways of describing infinite tree languages. The correspondence between $\mu$-Calculus and alternating tree automaton is used to solve the satisfiability and model checking problems by compiling the modal $\mu$-Calculus formula into an alternating tree automata. Thus advocating an automaton model specially tailored for working with modal $\mu$-Calculus. The advantage of the automaton model is its ability to deal with arbitrary branching in a much simpler way as compare to the one proposed by Janin and Walukiewicz. Both problems (i.e., model checking and satisfiability) are solved by reduction to the corresponding problems of alternating tree automata, namely to the acceptance and the non-emptiness problems, respectively. These problems, in turn, are solved using parity games where semantics of alternating tree automata is translated to a winning strategy in an appropriate parity game.