mohammad mousavi | Harward - Academia.edu (original) (raw)

Uploads

Papers by mohammad mousavi

Information Processing Letters, 2005

We propose a rule format that guarantees associativity of binary operators with respect to all no... more We propose a rule format that guarantees associativity of binary operators with respect to all notions of behavioral equivalence that are defined in terms of (im)possibility of transitions, e.g., the notions below strong bisimilarity in van Glabbeek’s spectrum. The initial format is a subset of the De Simone format. We show that all trivial generalizations of our format are bound for failure. We further extend the format in a few directions and illustrate its application to several formalisms in the literature. A subset of the format is studied to obtain associativity with respect to graph isomorphism.

Theoretical Computer Science, 2007

Electronic Notes in Theoretical Computer Science, 2006

We lay the foundations for a Structural Operational Semantics (SOS) framework for higher order pr... more We lay the foundations for a Structural Operational Semantics (SOS) framework for higher order processes. Then, we propose a number of extensions to Bernstein’s promoted tyft/tyxt format which aims at proving congruence of strong bisimilarity for higher order processes. The extended format is called promoted PANTH. This format is easier to apply and strictly more expressive than the promoted tyft/tyxt format. Furthermore, we propose and prove a congruence format for a notion of higher order bisimilarity arising naturally from our SOS framework. To illustrate our formats, we apply them to Thomsen’s Calculus of Higher Order Communicating Systems (CHOCS).

Information and Computation/information and Control, 2005

In this paper, we give novel and more liberal notions of operational and equational conservativit... more In this paper, we give novel and more liberal notions of operational and equational conservativity for language extensions. We motivate these notions by showing their practical application in existing formalisms. Based on our notions, we formulate and prove meta-theorems that establish conservative extensions for languages defined using Structural Operational Semantics (SOS).

There have been several timed extensions of ACP-style process algebras with successful terminatio... more There have been several timed extensions of ACP-style process algebras with successful termination. None of them, to our knowledge, are equationally conservative (ground-)extensions of ACP with successful termination. Here, we point out some design decisions which were the possible causes of this misfortune and by taking different decisions, we propose a spectrum of timed process algebras ordered by equational conservativity ordering.

Electronic Notes in Theoretical Computer Science, 2006

Electronic Notes in Theoretical Computer Science, 2006

Symmetry reduction is a promising technique for combatting state space explosion in model checkin... more Symmetry reduction is a promising technique for combatting state space explosion in model checking. The problem of finding the equivalence classes, i.e., the so-called orbits, of states under symmetry is a difficult problem known to be as hard as graph isomorphism. In this paper, we show how we can automatically find the orbits in an actor-based model, called Rebeca, without enforcing any restriction on the modeler. The proposed algorithm solves the orbit problem for Rebeca models in polynomial time. As a result, the simple actor-based Rebeca language can be utilized efficiently for modeling and verification of systems, without involving the modeler with the details of the verification technique implemented.

We present a formal semantics for a subset of Verilog, commonly used to describe cell libraries, ... more We present a formal semantics for a subset of Verilog, commonly used to describe cell libraries, in terms of transi- tion systems. Such transition systems can serve as input to symbolic model checking, for example equivalence checking with a transistor netlist description. We implement our for- mal semantics as an encoding from the subset of Verilog to the input language

Cell libraries often contain a simulation model in a system design language, such as Verilog. The... more Cell libraries often contain a simulation model in a system design language, such as Verilog. These languages usually involve non-determinism, which in turn, poses a challenge to their validation. Simulators often resolve such problems by using certain rules to make the specification deterministic. This however is not justified by the behavior of the hardware that is to be modeled. Hence, simulation might not be able to detect certain errors. In this paper we develop a technique to prove whether non-determinism does not affect the behavior of the simulation model, or whether there exists a situation in which the simulation model might produce different results. To make our technique efficient, we show that the global property of equal behavior for all possible evaluations is equivalent to checking only a certain local property.

Laryngoscope, 2003

The study was performed to investigate the possible association between opium dependency and lary... more The study was performed to investigate the possible association between opium dependency and laryngeal cancer. A hospital-based, group-matched, case-control study was presented. Ninety-eight patients with laryngeal cancer and 312 age- and gender-matched control subjects were selected at the otorhinolaryngology ward of a referral university-affiliated hospital. Data on cigarette smoking and alcohol and opium dependency were collected before surgery through semi-structured interview. The crude odds ratios of laryngeal cancer were 15.07 (95% confidence interval [CI], 6.92-32.8 [P <.0001]) for cigarette smoking, 21.55 (95% CI, 10.54-44 [P <.0001]) for opium dependency, and 1.84 (95% CI, 1.008-3.38 [P <.048]) for male gender. Because of strong associations, a logistic regression model was prepared; the odds ratio for gender in the final model was 0.87 (95% CI, 0.39-1.92 [P =.11]). According to the results, it seemed that gender was not an independent risk factor for laryngeal cancer. Also, the adjusted odds ratios for smoking (5.21) (95% CI, 2.33-11.67 [P <.002]) and opium dependency (10.74) (95% CI, 5.76-20.02 [P <.002]) were lower than the crude odds ratios, but both ratios were significant. The mean patient ages were 55.1 years (SD = 12.05 y) in opium-dependent patients and 65.6 years (SD = 12.8 y) in opium-nondependent patients (P =.01). The results of the study suggest that opium dependency is not only an independent possible risk factor for laryngeal cancer but also significantly increases the likelihood of developing of the disease at a younger age.

Information Processing Letters, 2005

We propose a rule format that guarantees associativity of binary operators with respect to all no... more We propose a rule format that guarantees associativity of binary operators with respect to all notions of behavioral equivalence that are defined in terms of (im)possibility of transitions, e.g., the notions below strong bisimilarity in van Glabbeek’s spectrum. The initial format is a subset of the De Simone format. We show that all trivial generalizations of our format are bound for failure. We further extend the format in a few directions and illustrate its application to several formalisms in the literature. A subset of the format is studied to obtain associativity with respect to graph isomorphism.

Theoretical Computer Science, 2007

Electronic Notes in Theoretical Computer Science, 2006

We lay the foundations for a Structural Operational Semantics (SOS) framework for higher order pr... more We lay the foundations for a Structural Operational Semantics (SOS) framework for higher order processes. Then, we propose a number of extensions to Bernstein’s promoted tyft/tyxt format which aims at proving congruence of strong bisimilarity for higher order processes. The extended format is called promoted PANTH. This format is easier to apply and strictly more expressive than the promoted tyft/tyxt format. Furthermore, we propose and prove a congruence format for a notion of higher order bisimilarity arising naturally from our SOS framework. To illustrate our formats, we apply them to Thomsen’s Calculus of Higher Order Communicating Systems (CHOCS).

Information and Computation/information and Control, 2005

In this paper, we give novel and more liberal notions of operational and equational conservativit... more In this paper, we give novel and more liberal notions of operational and equational conservativity for language extensions. We motivate these notions by showing their practical application in existing formalisms. Based on our notions, we formulate and prove meta-theorems that establish conservative extensions for languages defined using Structural Operational Semantics (SOS).

There have been several timed extensions of ACP-style process algebras with successful terminatio... more There have been several timed extensions of ACP-style process algebras with successful termination. None of them, to our knowledge, are equationally conservative (ground-)extensions of ACP with successful termination. Here, we point out some design decisions which were the possible causes of this misfortune and by taking different decisions, we propose a spectrum of timed process algebras ordered by equational conservativity ordering.

Electronic Notes in Theoretical Computer Science, 2006

Electronic Notes in Theoretical Computer Science, 2006

Symmetry reduction is a promising technique for combatting state space explosion in model checkin... more Symmetry reduction is a promising technique for combatting state space explosion in model checking. The problem of finding the equivalence classes, i.e., the so-called orbits, of states under symmetry is a difficult problem known to be as hard as graph isomorphism. In this paper, we show how we can automatically find the orbits in an actor-based model, called Rebeca, without enforcing any restriction on the modeler. The proposed algorithm solves the orbit problem for Rebeca models in polynomial time. As a result, the simple actor-based Rebeca language can be utilized efficiently for modeling and verification of systems, without involving the modeler with the details of the verification technique implemented.

We present a formal semantics for a subset of Verilog, commonly used to describe cell libraries, ... more We present a formal semantics for a subset of Verilog, commonly used to describe cell libraries, in terms of transi- tion systems. Such transition systems can serve as input to symbolic model checking, for example equivalence checking with a transistor netlist description. We implement our for- mal semantics as an encoding from the subset of Verilog to the input language

Cell libraries often contain a simulation model in a system design language, such as Verilog. The... more Cell libraries often contain a simulation model in a system design language, such as Verilog. These languages usually involve non-determinism, which in turn, poses a challenge to their validation. Simulators often resolve such problems by using certain rules to make the specification deterministic. This however is not justified by the behavior of the hardware that is to be modeled. Hence, simulation might not be able to detect certain errors. In this paper we develop a technique to prove whether non-determinism does not affect the behavior of the simulation model, or whether there exists a situation in which the simulation model might produce different results. To make our technique efficient, we show that the global property of equal behavior for all possible evaluations is equivalent to checking only a certain local property.

Laryngoscope, 2003

The study was performed to investigate the possible association between opium dependency and lary... more The study was performed to investigate the possible association between opium dependency and laryngeal cancer. A hospital-based, group-matched, case-control study was presented. Ninety-eight patients with laryngeal cancer and 312 age- and gender-matched control subjects were selected at the otorhinolaryngology ward of a referral university-affiliated hospital. Data on cigarette smoking and alcohol and opium dependency were collected before surgery through semi-structured interview. The crude odds ratios of laryngeal cancer were 15.07 (95% confidence interval [CI], 6.92-32.8 [P <.0001]) for cigarette smoking, 21.55 (95% CI, 10.54-44 [P <.0001]) for opium dependency, and 1.84 (95% CI, 1.008-3.38 [P <.048]) for male gender. Because of strong associations, a logistic regression model was prepared; the odds ratio for gender in the final model was 0.87 (95% CI, 0.39-1.92 [P =.11]). According to the results, it seemed that gender was not an independent risk factor for laryngeal cancer. Also, the adjusted odds ratios for smoking (5.21) (95% CI, 2.33-11.67 [P <.002]) and opium dependency (10.74) (95% CI, 5.76-20.02 [P <.002]) were lower than the crude odds ratios, but both ratios were significant. The mean patient ages were 55.1 years (SD = 12.05 y) in opium-dependent patients and 65.6 years (SD = 12.8 y) in opium-nondependent patients (P =.01). The results of the study suggest that opium dependency is not only an independent possible risk factor for laryngeal cancer but also significantly increases the likelihood of developing of the disease at a younger age.