Sharif Digital Repository

Description logic is a family of knowledge representive languages which represents knowledge via propositional logic (first order logic) propositions and constructors and applies its services for reasoning and consistency checking. Nowadays description logic and its popular reasoner FaCT++ which applies tablue reasoning technique are widely used in applications such as semantic web and onthologies. Model checking is a technique for systems and models verification and to guarantee the accuracy of design. Given a model description and a specification formula, the model checker verifies the model against the specification and decides if the model satisfies the description or not. Main model... 

Explicitly defining a software process is widely recognized as a necessary practice in software engineering and methodology engineering. However, this does not necessarily mean that the process thus defined is perfect, sound and useful. Evaluation of software processes has therefore become essential, and numerous evaluation approaches have been proposed to detect process inconsistencies and errors. As software processes are complex entities, it is very difficult to evaluate them manually; therefore, many evaluation methods, such as testing and simulation, are not adequate when precise verification of software processes is intended. The model checking approach can be effectively used for... 

According to increasing computer systems, needs for verification of such systems with respect to desirable properties is critical. Model checking is one of the best methods of verification. Different methods have been proposed for model checking. The most efficient of these methods is automata-theoretic approach. In this approach, formal specification of desirable property, specified by formula in temporal logics, is translated to corresponding automaton. If the system model is expressed as automaton, the problem of model checking is then reduced to a problem of automata-theory. The question is the following. Are all the computations of the corresponding automaton accepted by the automaton... 

Robotic Operating System (ROS) is an open source software framework, developed for the needs of robotics software developers and now it has become the standard ¬¬in this area. In this thesis, in order to propose an approach to verification of ROS-based softwares, we defined the mapping from Rebeca modeling language to ROS. To reach this aim, we have studied the main ROS concepts and investigated several ROS-based systems syntactically and operationally. Our mapping includes specifying the corresponding conceptual and syntactical components between Rebeca and ROS, and proposing an algorithm to convert any Rebeca code to the ROS code. We also have developed a tool to automate this conversion.... 

This thesis presents an integrated formal method for modeling and model checking of component based computing systems. Both components and coordination subsystems are modeled by a variant of standard labeled transition systems called record transition systems. A record transition system is a labeled transition system whose transition labels are records. We use records to model the concurrency of input – output operations in the ports of the system. The concurrency of the executions with respect to common transition labels are modeled by standard parallel composition operator and also a new defined operator called join which is analogous to the join operator defined to compose constraint... 

This thesis represents the theoritical concepts used for the implementation of a model checking framework for Reo specifications. This framework is implemented as a model checking tool which is applied to some case studies. First we have studied the wide variety of sementic models represented for Reo. We claim that the semantic model based on Büchi automata of records is a suitable candidate to serve as the underlying model of a model checking tool. Reo language represents some special features like synchronization, fairness and context dependency. Reo semantic models are analyzed with respect to their expressivness of the mentioned features. Moreover, the way that Büchi automata of records... 

Modeling and performance evaluation of the real time distributed systems is a significant problem. Stochastic activity network is one of the high level models used for this purpose. This network is an extension of generalized stochastic Petri net which is more powerful and flexible than other Petri net extensions. Checking the satisfiability of properties such as performance, dependability and user's expected properties is considerable in these models. Thus, using the approaches and generating modeling and model checking tools with the mentioned purpose is attractive. A model checker automatically checks the correctness of the system behaviors as properties against the model by getting the... 

With long-term evolution of large scale software systems, the study and engineering of architectural evolution becomes more and more important. In order to manage high level changes, the architects should plan the architecture evolution in a series of releases. Planning and analysis of architectural evolution is a challenge and plays a significant role in evolution management. An assessment solution could promote overall accuracy and quality of the evolution process. Compliance checking with expert-defined rules is a well-known assessment solution and could be applied in the field of architectural evolution. In this thesis, a solution is proposed in order to compliance check these evolution... 

In this thesis, we propose a method for verifing software component connectors. In this method, correctness of specification expressed using Linear Temporal Logic (LTL) will be checked on component connectors of Reo coordination model using Model Checking on Constraint Automata which is the behavioral model proposed for Reo connectors. Since model checking suffers from State Explosion Problem as the size of model increases, we reduce the impact of this problem using two techniques: using equivalence relations and implementing using Binary Decision Diagrams (BDDs). We find the smallest equivalent of our behavioral model according to CFFD equivalence which is weakest equivalence preserving... 

Vehicular ad-hoc networks have attracted the attention of many researchers during the last years due to the emergence of autonomous vehicles and the safety concerns regarding their use in near future. One of the major applications in this domain is the usage of vehicle to vehicle communication for warning message dissemination in dangerous situations to prevent more damage. A number of schemes have been proposed regarding the selection of forwarding nodes in this application and there is a need for developing frameworks for analysis and comparison of the schemes in fair situation. Most of the proposed frameworks make use of simulation techniques for the analysis of schemes. However, due to... 

Nowadays, one of the problems of network designers and users is the correctness of network equipment functionality. Since routers play an important role in information transfer between various networks and communicate with each other through a routing protocol, any violation of such protocol can result in the network's failure or defective transfer of data. Thus, being assured of the conformance of the implemented protocol in a router with what has been defined in the protocol's standard is of great significance. To this end, before using or exposing a router, network equipment testers should run protocol conformance tests on it and insure its correct functionality. This brings up the... 

In recent years, we have seen the proliferation of real-time and time-dependent systems. They have increased both in number and in complexity. Due to their increasing complexity, we need to model them and become assured of their correctness. Several formalisms have been devised for time-dependent systems. They include timed automaton and timed extensions of Petri nets. Our focus is on timed extension of activity networks and its model checking. Activity networksare powerful formalisms which allow designers to model the system in a natural, small and conceivable manner. This way, timed extension of activity networks can greatly help modelers. In this thesis, we propose a method to specify the... 

Some systems exhibit probabilistic and nondeterministic behavior. This behavior arises, for example, due to the use of randomized algorithms or presence of the unreliable components. Probabilistic Activity Network (PAN) is a flexible model for describing such systems. Every PAN is convertible to a Markov decision process. Up to now, there is no model checker which can operate directly on this model. In addition state space explosion arises as an important problem in model checking of real systems. We have developed a software tool called SPTMAN, for model checking of PAN. In this dissertation we are going to present a way for applying partial order reduction on PAN and then we will introduce... 

Verification of timed systems is concerned by many researchers in the last decades because of using these systems in critical applications. So, several models such as Timed Automat (TA) and Time Petri Nets (TPN) have been proposed for modeling these systems and variety of logics and abstraction methods are defined. One of the significant problems in timed system is cost-optimal reachability problem where, given an initial state and a target state, the task is to comput a path with infimum cost from initial state to the target state. Priced Timed Automat (PTA) introduce for solving cost-optimal reachability problems such as optimal scheduling and planing in timed systems. PTA is defined as an... 

The main goal of this thesis is to verify real-time properties of timed coordinated systems specified by timed-Reo circuits using the model checking techniqe. We use Timed Buchi Automata of Records (TBAR) as the semantics of timed-Reo. The model checking is done by converting Timed Buchi Automata of Records to an extension of Timed Automata that are usingas input of UPPAAL tool. We introduce a writer-automaton, which is synchronous with the desired Timed Automata, for initializing input ports. A tool that transforms Timed Buchi Automata of Records to UPPAAL Timed Automata has been implemented. Finally, two model checking case studies are examined by usingof our implemented tool over UPPAAL  

Meeting timing constraints is crucial for the correct behavior of embedded systems in modern vehicles. In the automotive domain, TADL2 Timing constraints are widely used and accepted standards for repetitive and critical timing requirements. However, ensuring these constraints in modern automotive systems, which encompass over 150 Electronic Control Units (ECUs), is challenging due to the increased complexity of automotive systems. Previous work proposed formal frameworks for specifying and verifying timing constraints, mostly based on timed automata, Time(d) Petri Nets, and TCTL logic for specification, which are the most prominent formalisms in the timed system's domain. They used UPPAAL...