Sharif Digital Repository

With the growth of semantic-aware environments, such as semantic web, new security requirements are imposed in access control procedures. An access control model for semantic web should take the semantic relationships (in three scopes of subject, object and action) into account in its access decisions. Considering the advantages of logic based models and description logic foundation of semantic web, we use the description logic as a basis to propose access control models in this environment. On the other hand, in some applications, such as e-banking environments, policy definition with the constraint(s) based on previous users’ accesses might be crucial. To consider this aspect, in this... 

Nowadays, BDI architecture is of the most well known agent’s architectures. BDI architecture or the architecture in which the system is viewed as rational agents based on the attitudes of belief, desire and intention represents an abstraction of human deliberation based on a theory of rational action in the human cognition process. BDI logic introduced by Rao and Georgeff have been widely used as the theoretical basis of specification and implementation of rational agents. BDI logic is limited to deal with crisp assertion, while the assertions encountered in real world are not precise and thus cannot be treated simply by using yes or no. Moreover, In order to obtain more human like agents we... 

In this thesis, we first study agent-based systems, and briefly review methods to formally describe such systems. One of these methods is theMetatem language. This language uses a form of linear-time temporal logic to describe the behavior of agents over time. We then introduce modal logics, and argue that they are well suited to describing agents’ knowledge in agent-based systems. We also introduceModal Logic of Knowledge, a combination of linear-time temporal and modal logics, using which temporal behavior of multi agent systems, along with knowledge of agents can be specified.Then, we review and implement a tableau based theorem-proving algorithm for this logic, which can be used as a... 

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... 

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...