  Solving Constrained Horn Clauses (CHCs) is a fundamental challenge behind a
wide range of verification and analysis tasks. Data-driven approaches show
great promise in improving CHC solving without the painstaking manual effort of
creating and tuning various heuristics. However, a large performance gap exists
between data-driven CHC solvers and symbolic reasoning-based solvers. In this
work, we develop a simple but effective framework, "Chronosymbolic Learning",
which unifies symbolic information and numerical data points to solve a CHC
system efficiently. We also present a simple instance of Chronosymbolic
Learning with a data-driven learner and a BMC-styled reasoner. Despite its
relative simplicity, experimental results show the efficacy and robustness of
our tool. It outperforms state-of-the-art CHC solvers on a dataset consisting
of 288 benchmarks, including many instances with non-linear integer
arithmetics.
