  We propose an automated method for checking the validity of a formula of
HFL(Z), a higher-order logic with fixpoint operators and integers. Combined
with Kobayashi et al.'s reduction from higher-order program verification to
HFL(Z) validity checking, our method yields a fully automated, uniform
verification method for arbitrary temporal properties of higher-order
functional programs expressible in the modal mu-calculus, including
termination, non-termination, fair termination, fair non-termination, and also
branching-time properties. We have implemented our method and obtained
promising experimental results.
