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.

@article{paperbot2097,
  title = {HFL(Z) Validity Checking for Automated Program Verification},
  author = {Naoki Kobayashi and Kento Tanahashi and Ryosuke Sato and Takeshi Tsukada},
  journal = {Proceedings of the ACM on Programming Languages},
  volume = {7},
  number = {POPL},
  year = {2023},
  doi = {10.1145/3571199}
}