Semantic web and formal design methods

Ph.DDOCTOR OF PHILOSOPH

Tools and verification techniques for integrated formal methods

Ph.DDOCTOR OF PHILOSOPH

Object-Z / TCOZ and Timed automata; Projection and integration

Ph.DDOCTOR OF PHILOSOPH

Complementary formalisms - synthesis, verification and visualization

Ph.DDOCTOR OF PHILOSOPH

A formal modeling approach to ontology engineering

Ph.DDOCTOR OF PHILOSOPH

Extending and Relating Semantic Models of Compensating CSP

Business transactions involve multiple partners coordinating and interacting with each other. These transactions have hierarchies of activities which need to be orchestrated. Usual database approaches (e.g.,checkpoint, rollback) are not applicable to handle faults in a long running transaction due to interaction with multiple partners. The compensation mechanism handles faults that can arise in a long running transaction. Based on the framework of Hoare's CSP process algebra, Butler et al introduced Compensating CSP (cCSP), a language to model long-running transactions. The language introduces a method to declare a transaction as a process and it has constructs for orchestration of compensation. Butler et al also defines a trace semantics for cCSP. In this thesis, the semantic models of compensating CSP are extended by defining an operational semantics, describing how the state of a program changes during its execution. The semantics is encoded into Prolog to animate the specification. The semantic models are further extended to define the synchronisation of processes. The notion of partial behaviour is defined to model the behaviour of deadlock that arises during process synchronisation. A correspondence relationship is then defined between the semantic models and proved by using structural induction. Proving the correspondence means that any of the presentation can be accepted as a primary definition of the meaning of the language and each definition can be used correctly at different times, and for different purposes. The semantic models and their relationships are mechanised by using the theorem prover PVS. The semantic models are embedded in PVS by using Shallow embedding. The relationships between semantic models are proved by mutual structural induction. The mechanisation overcomes the problems in hand proofs and improves the scalability of the approach

Reasoning about complex agent knowledge - Ontologies, Uncertainty, rules and beyond

Ph.DDOCTOR OF PHILOSOPH

Onto4CAAL: An Ontology to Support Requirements Specification in the Development of AAL (Ambient Assisted Living) Systems

The Ambient Assisted Living (AAL) is a technological approach that emerged to meet the demands of the elderly and people with disabilities. As they are considered complex and multidisciplinary systems, it is necessary to identify and define which modules need to compose these systems. Among the challenges found in the development of the AAL systems are the alignment with functional and/or non-functional requirements and the compliance with ethical, legal, social, medical and technical restrictions that guide these types of systems. Therefore, this work presents a core ontology (Onto4CAAL) to support the specification of requirements in AAL systems, where the elements that are part of the system type are integrated. Using this ontology, it was possible to develop a domain ontology (Onto4Elev) for Vertical Lift Platforms, where a validation was carried out with the industry in relation to the elements that constitute it and, later, a scenario was built for the application simulation and verification. With the use of ontology, it will be possible to standardize the understanding of the associated terms and, at the same time, to verify the relationship among the elements, helping the designer in the decision making

Towards verification of computation orchestration

Recently, a promising programming model called Orc has been proposed to support a structured way of orchestrating distributed Web Services. Orc is intuitive because it offers concise constructors to manage concurrent communication, time-outs, priorities, failure of Web Services or communication and so forth. The semantics of Orc is precisely defined. However, there is no automatic verification tool available to verify critical properties against Orc programs. Our goal is to verify the orchestration programs (written in Orc language) which invoke web services to achieve certain goals. To investigate this problem and build useful tools, we explore in two directions. Firstly, we define a Timed Automata semantics for the Orc language, which we prove is semantically equivalent to the operational semantics of Orc. Consequently, Timed Automata models are systematically constructed from Orc programs. The practical implication is that existing tool supports for Timed Automata, e.g., Uppaal, can be used to simulate and model check Orc programs. An experimental tool has been implemented to automate this approach. Secondly, we start with encoding the operational semantics of Orc language in Constraint Logic Programming (CLP), which allows a systematic translation from Orc to CLP. Powerful constraint solvers like CLP(R) are then used to prove traditional safety properties and beyond, e.g., reachability, deadlock-freeness, lower or upper bound of a time interval, etc. Counterexamples are generated when properties are not satisfied. Furthermore, the stepwise execution traces can be automatically generated as the simulation steps. The two different approaches give an insight into the verification problem of Web Service orchestration. The Timed Automata approach has its merits in visualized simulation and efficient verification supported by the well developed tools. On the other hand, the CPL approach gives better expressiveness in both modeling and verification. The two approaches complement each other, which gives a complete solution for the simulation and verification of Computation Orchestration

Model checking concurrent and real-time systems : the PAT approach

Ph.DDOCTOR OF PHILOSOPH