Authors: Parosh Aziz Abdulla, Mohamed Faouzi Atig, Yu-Fang Chen, Lukas Holik, Ahmed Rezine, Philipp Rummer, and Jari Stenman
Abstract: We present a decision procedure for a logic that combines (i) word equations over string variables denoting words of arbitrary lengths, together with (ii) constraints on the length of words, and on (iii) the regular languages to which words belong. Decidability of this general logic is still open. Our procedure is sound for the general logic, and a decision procedure for a particularly rich fragment that restricts the form in which word equations are written. In contrast to many ex- isting procedures, our method does not make assumptions about the maximum length of words. We have developed a prototypical implemen- tation of our decision procedure, and integrated it into a CEGAR-based model checker for the analysis of programs encoded as Horn clauses. Our tool is able to automatically establish the correctness of several programs that are beyond the reach of existing methods.
In Proceedings of the 26th International Conference on Computer Aided Verification (CAV 2014)
Last version (pdf) 2014