Betim Musa

Ultimate Automizer with Array Interpolation

Ultimate Automizer is a software verification tool that is able to analyze reachability of an error label, memory safety, and termination of C programs. For all three tasks, our tool follows an automata-based approach where interpolation is used to compute proofs for traces. The interpolants are generated via a new scheme that requires only the post operator, unsatisfiable cores and live variable analysis. This new scheme enables our tool to use the SMT theory of arrays in combination with interpolation.

Ultimate Automizer with Two-track Proofs

Ultimate Automizer is a software verification tool that implements an automata-based approach for the analysis of safety and liveness problems. The version that participates in this years competition is able to analyze non-reachability, memory safety, termination, and overflow problems. In this paper we present the new features of our tool as well as the instructions how to install and use it.

Ultimate Automizer with an On-Demand Construction of Floyd-Hoare Automata

Ultimate Automizer is a software verifier that implements an automata-based approach for the verification of safety and liveness properties. A central new feature that speeded up the abstraction refinement of the tool is an on-demand construction of Floyd-Hoare automata.

Craig vs. Newton in software model checking

Ever since the seminal work on SLAM and BLAST, software model checking with counterexample-guided abstraction refinement (CEGAR) has been an active topic of research. The crucial procedure here is to analyze a sequence of program statements (the counterexample) to find building blocks for the overall proof of the program. We can distinguish two approaches (which we name Craig and Newton) to implement the procedure. The historically first approach, Newton (named after the tool from the SLAM toolkit), is based on symbolic execution. The second approach, Craig, is based on Craig interpolation. It was widely believed that Craig is substantially more effective than Newton. In fact, 12 out of the 15 CEGAR-based tools in SV-COMP are based on Craig. Advances in software model checkers based on Craig, however, can go only lockstep with advances in SMT solvers with Craig interpolation. It may be time to revisit Newton and ask whether Newton can be as effective as Craig. We have implemented a total of 11 variants of Craig and Newton in two different state-of-the-art software model checking tools and present the outcome of our experimental comparison.

Ultimate Automizer with Unsatisfiable Cores

Ultimate Automizer is an automatic software verification tool for C programs. This tool is a prototype implementation of an automata-theoretic approach that allows a modular verification of programs. Furthermore, this is the first implementation of a novel interpolation technique where interpolants are not obtained from an interpolating theorem prover but from a combination of a live variable analysis, interprocedural predicate transformers and unsatisfiable cores.

Ultimate Automizer and the Search for Perfect Interpolants

Ultimate Automizer is a software verifier that generalizes proofs for traces to proofs for larger parts for the program. In recent years the portfolio of proof producers that are available to Ultimate has grown continuously. This is not only because more trace analysis algorithms have been implemented in Ultimate but also due to the continuous progress in the SMT community. In this paper we explain how Ultimate Automizer dynamically selects trace analysis algorithms and how the tool decides when proofs for traces are “good” enough for using them in the abstraction refinement.