Solving String Constraints with Approximate Parikh Image

In this paper, we propose a refined version of the Parikh image abstraction of finite automata to resolve string length constraints. We integrate this abstraction into the string solver SLOTH, where on top of handling length constraints, our abstraction is also used to speed-up solving other types of constraints. The experimental results show that our extension of SLOTH has good results on simple benchmarks as well as on complex benchmarks that are real-word combinations of transducer and concatenation constraints.