Formalising control in robust spoken dialogue systems

The spoken language interface is now becoming an in-creasingly serious research topic with application to a wide range of highly engineered systems. Such systems not only include innocuous human-computer interactions, but also encompass shared-control safety critical devices such as automotive vehicles and robotic systems. Spoken Dialogue Systems (SDS) are the language architecture used to provide linguistic interaction in these applications, but they have to date been notoriously difficult to engineer in a robust and safe manner. In this paper we report on our efforts to im-prove the safety and overall usability of dialogue enabled applications through the employment of formal methods in SDS development and testing. Specifically, we use Commu-nicating Sequential Processes (CSP) as the basis of a new approach to the specification, design and verification of dia-logue manager control. Moreover, to support this approach, we introduce FDMSC – the Formal Dialogue Management for Shared Control toolkit – and illustrate its use in the con-struction of formal methods based spoken dialogue systems. 1

A Graph Transformation Approach for Modeling and Verification of UML 2.0 Sequence Diagrams

Unified Modeling Language (UML) 2.0 Sequence Diagrams (UML 2.0 SD) are used to describe interactions in software systems. These diagrams must be verified in the early stages of software development process to guarantee the production of a reliable system. However, UML 2.0 SD lack formal semantics as all UML specifications, which makes their verification difficult, especially if we are modeling a critical system where the automation of verification is necessary. Communicating Sequential Processes (CSP) is a formal specification language that is suited for analysis and has many automatic verification tools. Thus, UML and CSP have complementary aspects, which are modeling and analysis. Recently, a formalization of UML 2.0 SD using CSP has been proposed in the literature; however, no automation of that formalization exists. In this paper, we propose an approach on the basis of the above formalization and a visual modeling tool to model and automatically transform UML 2.0 SD to CSP ones; thus, the existing CSP model checker can verify them. This approach aims to use UML 2.0 SD for modeling and CSP and its tools for verification. This approach is based on graph transformation, which uses AToM3 tool and proposes a metamodel of UML 2.0 SD and a graph grammar to perform the mapping of the latter into CSP. Failures-Divergence Refinement (FDR) is the model checking tool used to verify the behavioral properties of the source model transformation such as deadlock, livelock and determinism. The proposed approach and tool are illustrated through a case study

Security and Performance Verification of Distributed Authentication and Authorization Tools

Parallel distributed systems are widely used for dealing with massive data sets and high performance computing. Securing parallel distributed systems is problematic. Centralized security tools are likely to cause bottlenecks and introduce a single point of failure. In this paper, we introduce existing distributed authentication and authorization tools. We evaluate the quality of the security tools by verifying their security and performance. For security tool verification, we use process calculus and mathematical modeling languages. Casper, Communicating Sequential Process (CSP) and Failure Divergence Refinement (FDR) to test for security vulnerabilities, Petri nets and Karp Miller trees are used to find performance issues of distributed authentication and authorization methods. Kerberos, PERMIS, and Shibboleth are evaluated. Kerberos is a ticket based distributed authentication service, PERMIS is a role and attribute based distributed authorization service, and Shibboleth is an integration solution for federated single sign-on authentication. We find no critical security and performance issues