Construction of Verifier Combinations Based on Off-the-Shelf Verifiers

Software verifiers have different strengths and weaknesses, depending on properties of the verification task. It is well-known that combinations of verifiers via portfolio and selection approaches can help to combine the strengths. In this paper, we investigate (a) how to easily compose such combinations from existing, ‘off-the-shelf’ verification tools without changing them and (b) how much performance improvement easy combinations can yield, regarding the effectiveness (number of solved problems) and efficiency (consumed resources). First, we contribute a method to systematically and conveniently construct verifier combinations from existing tools, using the composition framework CoVeriTeam. We consider sequential portfolios, parallel portfolios, and algorithm selections. Second, we perform a large experiment on 8 883 verification tasks to show that combinations can improve the verification results without additional computational resources. All combinations are constructed from off-the-shelf verifiers, that is, we use them as published. The result of our work suggests that users of verification tools can achieve a significant improvement at a negligible cost (only configure our composition scripts).