Our recently proposed certification framework for bit-level k-induction-based model checking has ... more Our recently proposed certification framework for bit-level k-induction-based model checking has been shown to be quite effective in increasing the trust of verification results even though it partially involved quantifier reasoning. In this paper we show how to simplify the approach by assuming reset functions to be stratified. This way it can be lifted to word-level and in principle to other theories where quantifier reasoning is difficult. Our new method requires six simple SAT checks and one polynomial-time check, allowing certification to remain in co-NP while the previous approach required five SAT checks and one QBF check. Experimental results show a substantial performance gain for our new approach. Finally we present and evaluate our new tool CERTIFAIGER-WL which is able to certify k-induction-based word-level model checking.
We present a formal framework to certify k-induction-based model checking results. The key idea i... more We present a formal framework to certify k-induction-based model checking results. The key idea is the notion of a k-witness circuit which simulates the given circuit and has a simple inductive invariant serving as proof certificate. Our approach allows to check proofs with an independent proof checker by reducing the certification problem to pure SAT checks and checking a simple QBF with one quantifier alternation. We also present Certifaiger, the resulting certification toolkit, and evaluate it on instances from the hardware model checking competition. Our experiments show the practical use of our certification method.
Communications in computer and information science, 2020
We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framewor... more We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framework automatically translates the verification of system models against properties formulated in computation tree logics with epistemic modalities (CTLK) into quantified Boolean formulas (QBFs). Our framework exploits recent QBF technology for solving those verification problems and for certifying the result, making the implementation of a dedicated CTLK solver obsolete. The translation to QBF is based on existing theoretical work and implemented in our novel tool Open image in new window which extends the open-source model checker MCMAS. First experimental results are very promising and indicate the practical feasibility of our approach. Furthermore we provide novel benchmarks to the QBF community.
Proceedings of the ... AAAI Conference on Artificial Intelligence, Apr 3, 2020
We study the problem of verifying multi-agent systems under the assumption of bounded recall. We ... more We study the problem of verifying multi-agent systems under the assumption of bounded recall. We introduce the logic CTLK BR , a bounded-recall variant of the temporalepistemic logic CTLK. We define and study the model checking problem against CTLK specifications under incomplete information and bounded recall and present complexity upper bounds. We present an extension of the BDD-based model checker MCMAS implementing model checking under bounded recall semantics and discuss the experimental results obtained.
Communications in Computer and Information Science, 2020
We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framewor... more We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framework automatically translates the verification of system models against properties formulated in computation tree logics with epistemic modalities (CTLK) into quantified Boolean formulas (QBFs). Our framework exploits recent QBF technology for solving those verification problems and for certifying the result, making the implementation of a dedicated CTLK solver obsolete. The translation to QBF is based on existing theoretical work and implemented in our novel tool Open image in new window which extends the open-source model checker MCMAS. First experimental results are very promising and indicate the practical feasibility of our approach. Furthermore we provide novel benchmarks to the QBF community.
The model checking problem for multi-agent systems against specifications in the alternating-time... more The model checking problem for multi-agent systems against specifications in the alternating-time temporal logic AT L, hence AT L∗ , under perfect recall and imperfect information is known to be undecidable. To tackle this problem, in this paper we investigate a notion of bounded recall under incomplete information. We present a novel three-valued semantics for AT L∗ in this setting and analyse the corresponding model checking problem. We show that the three-valued semantics here introduced is an approximation of the classic two-valued semantics, then give a sound, albeit partial, algorithm for model checking two-valued perfect recall via its approximation as three-valued bounded recall. Finally, we extend MCMAS, an open-source model checker for AT L and other agent specifications, to incorporate bounded recall; we illustrate its use and present experimental results.
Proceedings of the AAAI Conference on Artificial Intelligence, 2020
We study the problem of verifying multi-agent systems under the assumption of bounded recall. We ... more We study the problem of verifying multi-agent systems under the assumption of bounded recall. We introduce the logic CTLKBR, a bounded-recall variant of the temporal-epistemic logic CTLK. We define and study the model checking problem against CTLK specifications under incomplete information and bounded recall and present complexity upper bounds. We present an extension of the BDD-based model checker MCMAS implementing model checking under bounded recall semantics and discuss the experimental results obtained.
Certification helps to increase trust in formal verification of safety-critical systems which req... more Certification helps to increase trust in formal verification of safety-critical systems which require assurance on their correctness. In hardware model checking, a widely used formal verification technique, phase abstraction is considered one of the most commonly used preprocessing techniques. We present an approach to certify an extended form of phase abstraction using a generic certificate format. As in earlier works our approach involves constructing a witness circuit with an inductive invariant property that certifies the correctness of the entire model checking process, which is then validated by an independent certificate checker. We have implemented and evaluated the proposed approach including certification for various preprocessing configurations on hardware model checking competition benchmarks. As an improvement on previous work in this area, the proposed method is able to efficiently complete certification with an overhead of a fraction of model checking time.
Our recently proposed certification framework for bit-level k-induction-based model checking has ... more Our recently proposed certification framework for bit-level k-induction-based model checking has been shown to be quite effective in increasing the trust of verification results even though it partially involved quantifier reasoning. In this paper we show how to simplify the approach by assuming reset functions to be stratified. This way it can be lifted to word-level and in principle to other theories where quantifier reasoning is difficult. Our new method requires six simple SAT checks and one polynomial-time check, allowing certification to remain in co-NP while the previous approach required five SAT checks and one QBF check. Experimental results show a substantial performance gain for our new approach. Finally we present and evaluate our new tool CERTIFAIGER-WL which is able to certify k-induction-based word-level model checking.
We present a formal framework to certify k-induction-based model checking results. The key idea i... more We present a formal framework to certify k-induction-based model checking results. The key idea is the notion of a k-witness circuit which simulates the given circuit and has a simple inductive invariant serving as proof certificate. Our approach allows to check proofs with an independent proof checker by reducing the certification problem to pure SAT checks and checking a simple QBF with one quantifier alternation. We also present Certifaiger, the resulting certification toolkit, and evaluate it on instances from the hardware model checking competition. Our experiments show the practical use of our certification method.
Communications in computer and information science, 2020
We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framewor... more We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framework automatically translates the verification of system models against properties formulated in computation tree logics with epistemic modalities (CTLK) into quantified Boolean formulas (QBFs). Our framework exploits recent QBF technology for solving those verification problems and for certifying the result, making the implementation of a dedicated CTLK solver obsolete. The translation to QBF is based on existing theoretical work and implemented in our novel tool Open image in new window which extends the open-source model checker MCMAS. First experimental results are very promising and indicate the practical feasibility of our approach. Furthermore we provide novel benchmarks to the QBF community.
Proceedings of the ... AAAI Conference on Artificial Intelligence, Apr 3, 2020
We study the problem of verifying multi-agent systems under the assumption of bounded recall. We ... more We study the problem of verifying multi-agent systems under the assumption of bounded recall. We introduce the logic CTLK BR , a bounded-recall variant of the temporalepistemic logic CTLK. We define and study the model checking problem against CTLK specifications under incomplete information and bounded recall and present complexity upper bounds. We present an extension of the BDD-based model checker MCMAS implementing model checking under bounded recall semantics and discuss the experimental results obtained.
Communications in Computer and Information Science, 2020
We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framewor... more We present a novel bounded model checking (BMC) tool chain for multi-agent systems. This framework automatically translates the verification of system models against properties formulated in computation tree logics with epistemic modalities (CTLK) into quantified Boolean formulas (QBFs). Our framework exploits recent QBF technology for solving those verification problems and for certifying the result, making the implementation of a dedicated CTLK solver obsolete. The translation to QBF is based on existing theoretical work and implemented in our novel tool Open image in new window which extends the open-source model checker MCMAS. First experimental results are very promising and indicate the practical feasibility of our approach. Furthermore we provide novel benchmarks to the QBF community.
The model checking problem for multi-agent systems against specifications in the alternating-time... more The model checking problem for multi-agent systems against specifications in the alternating-time temporal logic AT L, hence AT L∗ , under perfect recall and imperfect information is known to be undecidable. To tackle this problem, in this paper we investigate a notion of bounded recall under incomplete information. We present a novel three-valued semantics for AT L∗ in this setting and analyse the corresponding model checking problem. We show that the three-valued semantics here introduced is an approximation of the classic two-valued semantics, then give a sound, albeit partial, algorithm for model checking two-valued perfect recall via its approximation as three-valued bounded recall. Finally, we extend MCMAS, an open-source model checker for AT L and other agent specifications, to incorporate bounded recall; we illustrate its use and present experimental results.
Proceedings of the AAAI Conference on Artificial Intelligence, 2020
We study the problem of verifying multi-agent systems under the assumption of bounded recall. We ... more We study the problem of verifying multi-agent systems under the assumption of bounded recall. We introduce the logic CTLKBR, a bounded-recall variant of the temporal-epistemic logic CTLK. We define and study the model checking problem against CTLK specifications under incomplete information and bounded recall and present complexity upper bounds. We present an extension of the BDD-based model checker MCMAS implementing model checking under bounded recall semantics and discuss the experimental results obtained.
Certification helps to increase trust in formal verification of safety-critical systems which req... more Certification helps to increase trust in formal verification of safety-critical systems which require assurance on their correctness. In hardware model checking, a widely used formal verification technique, phase abstraction is considered one of the most commonly used preprocessing techniques. We present an approach to certify an extended form of phase abstraction using a generic certificate format. As in earlier works our approach involves constructing a witness circuit with an inductive invariant property that certifies the correctness of the entire model checking process, which is then validated by an independent certificate checker. We have implemented and evaluated the proposed approach including certification for various preprocessing configurations on hardware model checking competition benchmarks. As an improvement on previous work in this area, the proposed method is able to efficiently complete certification with an overhead of a fraction of model checking time.
Uploads
Papers by Emily Yu