The OpenSMT Solver

Bruttomesso, Roberto; Pek, Edgar; Sharygina, Natasha; Tsitovich, Aliaksei

doi:10.1007/978-3-642-12002-2_12

Cited by 88 publications

(55 citation statements)

References 6 publications

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“…Furthermore, the SAT-based solving approach continues to find various new application domains today. Conflict-driven clause learning (CDCL) SAT solvers are at the heart of SMT solvers, and in some cases such as the theory of bit-vectors, most state-of-the-art SMT solvers are based on bit-blasting and use pure SAT solvers for actual solving (including [21,15,11,10,31,12]). This gives motivation for developing even more efficient solving techniques for SAT.…”

Section: Introductionmentioning

confidence: 99%

Simulating Circuit-Level Simplifications on CNF

2011

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Boolean satisfiability (SAT) and its extensions have become a core technology in many application domains, such as planning and formal verification, and continue finding various new application domains today. The SAT-based approach divides into three steps: encoding, preprocessing, and search. It is often argued that by encoding arbitrary Boolean formulas in conjunctive normal form (CNF), structural properties of the original problem are not reflected in the CNF. This should result in the fact that CNF-level preprocessing and SAT solver techniques have an inherent disadvantage compared to related techniques applicable on the level of more structural SAT instance representations such as Boolean circuits. Motivated by this, various simplification techniques and intricate CNF encodings for circuit-level SAT instance representations have been proposed. On the other hand, based on the highly efficient CNF-level clause learning SAT solvers, there is also strong support for the claim that CNF is sufficient as an input format for SAT solvers.In this work we study the effect of CNF-level simplification techniques, focusing on SatElite-style variable elimination (VE) and what we call blocked clause elimination (BCE). We show that BCE is surprisingly effective both in theory and in practice on CNF formulas resulting from a standard CNF encoding for circuits: without explicit knowledge of the underlying circuit structure, it achieves the same level of simplification as a combination of circuit-level simplifications and previously suggested polarity-based CNF encodings. We also show that VE can achieve many of the same effects as BCE, but not all. On the other hand, it turns out that VE and BCE are indeed partially orthogonal techniques. We also study 2 the practical effects of combining BCE and VE for reducing the size of formulas and on the running times of state-of-the-art SAT solvers. Furthermore, we address the problem of how to construct original witnesses to satisfiable CNF formulas when applying a combination of BCE and VE.

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Section: Introductionmentioning

confidence: 99%

Simulating Circuit-Level Simplifications on CNF

2011

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“…We implemented our algorithms within an open source SMT solver OpenSMT [5]. We applied our algorithms to the resolution proofs obtained by OpenSMT for 198 unsatisfiable examples from plain MUS track of SAT11 competition.…”

Section: Methodsmentioning

confidence: 99%

“…We have implemented our algorithms in OpenSMT [5] and applied them on unsatisfiable proofs of 198 examples from plain MUS track of SAT11 competition. The original algorithm removes 11.97% of clauses in the proofs of the examples.…”

Section: Introductionmentioning

confidence: 99%

Improved Single Pass Algorithms for Resolution Proof Reduction

Gupta

2012

Theory and Applications of Satisfiability Testing – SAT 2012

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Abstract. Unsatisfiability proofs find many applications in verification. Today, many SAT solvers are capable of producing resolution proofs of unsatisfiability. For efficiency smaller proofs are preferred over bigger ones. The solvers apply proof reduction methods to remove redundant parts of the proofs while and after generating the proofs. One method of reducing resolution proofs is redundant resolution reduction, i.e., removing repeated pivots in the paths of resolution proofs (aka Pivot recycle). The known single pass algorithm only tries to remove redundancies in the parts of the proof that are trees. In this paper, we present three modifications to improve the algorithm such that the redundancies can be found in the parts of the proofs that are DAGs. The first modified algorithm covers greater number of redundancies as compared to the known algorithm without incurring any additional cost. The second modified algorithm covers even greater number of the redundancies but it may have longer run times. Our third modified algorithm is parametrized and can trade off between run times and the coverage of the redundancies. We have implemented our algorithms in OpenSMT and applied them on unsatisfiability proofs of 198 examples from plain MUS track of SAT11 competition. The first and second algorithm additionally remove 0.89% and 10.57% of clauses respectively as compared to the original algorithm. For certain value of the parameter, the third algorithm removes almost as many clauses as the second algorithm but is significantly faster.

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“…The eVolCheck tool itself consists of a comparator that identifies the changed functions and function calls, a call graph traversal that attempts to check summaries of all the modified functions bottom up, an upward refiner that identifies parent functions to be rechecked when a summary check fails, and a summary checker that performs the actual check of a function against its summary. The summary checker in turn consists of a PBMC encoder that takes care of unwinding loops and recursion, generation of SSA form and bit-blasting, a solver wrapper that takes care of communication with the solver/interpolator (OpenSMT [2]), and a downward refiner that identifies ancestor functions to be refined when a summary check fails possibly due to imprecise representation of the ancestor function calls. Additionally, there are two optional optimizations in eVolCheck, namely slicing and summary optimization.…”

Section: Tool Architecturementioning

confidence: 99%

eVolCheck: Incremental Upgrade Checker for C

Fedyukovich

Šerý

Sharygina

2013

Tools and Algorithms for the Construction and Analysis of Systems

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Software is not created at once. Rather, it grows incrementally version by version and evolves long after being first released. To be practical for software developers, the software verification tools should be able to cope with changes. In this paper, we present a tool, eVolCheck, that focuses on incremental verification of software as it evolves. During the software evolution the tool maintains abstractions of program functions, function summaries, derived using Craig interpolation. In each check, the function summaries are used to localize verification of an upgrade to analysis of the modified functions. Experimental evaluation on a range of various benchmarks shows substantial speedup of incremental upgrade checking of eVolCheck in contrast to checking each version from scratch.

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The OpenSMT Solver

Cited by 88 publications

References 6 publications

Simulating Circuit-Level Simplifications on CNF

Simulating Circuit-Level Simplifications on CNF

Improved Single Pass Algorithms for Resolution Proof Reduction

eVolCheck: Incremental Upgrade Checker for C

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