Refining Interval Temporal Logic specifications (1997)

by A Cau, H Zedan
Venue:In Proceedings of the 4th International AMAST Workshop on Real-Time Systems and Concurrent and Distributed Software (ARTS ’97), volume 1231 of LNCS
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A compositional framework for access control policies enforcement

by François Siewe, Antonio Cau, Hussein Zedan - In FMSE , 2003
"... Despite considerable number of work on authorization models, enforcing multiple policies is still a challenge in order to achieve the level of security required in many real-world systems. Moreover current approaches address security settings independently, and their incorporation into systems devel ..."
Abstract - Cited by 25 (3 self) - Add to MetaCart
Despite considerable number of work on authorization models, enforcing multiple policies is still a challenge in order to achieve the level of security required in many real-world systems. Moreover current approaches address security settings independently, and their incorporation into systems development lifecycle is not well understood. This paper presents a formal model for the specification of access control policies. The approach can handle the enforcement of multiple policies through policies composition. Temporal dependencies among authorizations can be formulated. Interval Temporal Logic (ITL) is our underlying formal framework and policies are modeled as safety properties expressing how authorizations are granted over time. The approach is compositional, and can be used to specify other system’s properties such as functional and temporal requirements. The use of a common formalism eases the integration of security requirements into system requirements so that they can be reasoned about uniformly throughout the development lifecycle. Furthermore specification of policies are executable in Tempura, a simulation tool for ITL.
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A Tableau Method for Interval Temporal Logic

by Howard Bowman, Simon Thompson - In TABLEAUX'98, International Conference on Analytic Tableaux and Related Methods , 1998
"... this paper we do present a complete tableau method for interval temporal logic and we include the projection operator. Central to our strategy is the identification of normal forms for all the operators of our logic. In effect, these normal forms give inductive definitions of the ITL operators. Then ..."
Abstract - Cited by 7 (0 self) - Add to MetaCart
this paper we do present a complete tableau method for interval temporal logic and we include the projection operator. Central to our strategy is the identification of normal forms for all the operators of our logic. In effect, these normal forms give inductive definitions of the ITL operators. Then, in the style of Wolper [17], we define a tableau decision procedure to check satisfiability of our logic. For simplicity of presentation we work in the propositional setting

Formal Methods For The Re-Engineering of Computing Systems

by X. Liu, H. Yang, H. Zedan - In Proceedings of The 21st IEEE International Conference on Computer Software and Application (COMPSAC'97 , 1997
"... We present a short review of formal methods and their use in the re-engineering of computing systems. The paper considers five classes of formal notations and theories, namely state/model-based, logic-based, algebraic-based, process algebra and net-based formalisms together with combined formalisms ..."
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We present a short review of formal methods and their use in the re-engineering of computing systems. The paper considers five classes of formal notations and theories, namely state/model-based, logic-based, algebraic-based, process algebra and net-based formalisms together with combined formalisms. Keywords : formal methods, re-engineering, wide spectrum language, real-time systems, refinement, reverse engineering, logic. Contents 1 INTRODUCTION 2 2 CLASSIFICATION OF FORMAL METHODS 4 2.1 Model-based Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.2 Logic-based Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.3 Algebraic Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.4 Process Algebra Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.5 Net-Based Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3 CRITERIA AND RESULTS 17 4 DISCUSS...
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Integrating Structured OO Approaches with Formal Techniques for the Development of Real-time Systems

by Z. Chen, A. Cau, H. Zedan, H. Yang - International Journal of Information and Software Technology , 1999
"... The use of formal methods in the development of time-critical applications is essential if we want to achieve a high level of assurance in them. However, these methods have not yet been widely accepted in industry as compared to the more established structured and informal techniques. A reliable lin ..."
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The use of formal methods in the development of time-critical applications is essential if we want to achieve a high level of assurance in them. However, these methods have not yet been widely accepted in industry as compared to the more established structured and informal techniques. A reliable linkage between these two techniques will provide the developer with a powerful tool for developing a provably correct system. In this paper, we explore the issue of integrating a real-time formal technique, TAM (Temporal Agent Model), with an industry-strength structured methodology known as HRT-HOOD. TAM is a systematic formal approach for the development of real-time systems based on the refinement calculus. Within TAM, a formal specification can be written (in a logic-based formalism), analysed and then refined to concrete representation through successive applications of sound refinement laws. Both abstract specification and concrete implementation are allowed to freely intermix. HRT-HOOD ...
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A Wide-Spectrum Language for Object-Based Development of Real-time Systems

by Z. Chen, H. Zedan, A. Cau, H. Yang - International Journal of Information Sciences , 1999
"... A formal design notation is presented whose underlying computational model is objectbased. The object structure of the model is based on the practical, industry-strength Object Oriented structured development technique HRT-HOOD. The computational model has been specifically chosen because it leads t ..."
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A formal design notation is presented whose underlying computational model is objectbased. The object structure of the model is based on the practical, industry-strength Object Oriented structured development technique HRT-HOOD. The computational model has been specifically chosen because it leads to designs which can be analyzed for their schedulability in a distributed hard real-time execution environment. It is a wide-spectrum language supporting abstract description statements in Interval Temporal Logic (ITL) for the description of the timing, functional, and communication behavior of the proposed realtime system, and concrete Temporal Agent Model (TAM) statements with objects which can be directly executed. The semantics of these concrete statements is defined denotationally in specification-oriented style using ITL. A system specified at a high level of abstraction can be systematically transformed into an executable program by the use of sound ITL refinement rules. Key words: o...
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A Hierarchical Completeness Proof for Interval Temporal Logic with Finite Time

by B. C. Moszkowski, Leicester Le Bh , 2003
"... Logics based on regular languages over finite words and #-words o#er a promising but elusive framework for formal specification and verification. Starting with the seminal work of Buchi [5, 6] and Elgot [11] around 1960, a number of such logics and decision procedures have been proposed. ..."
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Logics based on regular languages over finite words and #-words o#er a promising but elusive framework for formal specification and verification. Starting with the seminal work of Buchi [5, 6] and Elgot [11] around 1960, a number of such logics and decision procedures have been proposed.

Compositional Modelling: The Formal Perspective

by Hussein Zedan, Antonio Cau, Ben Moszkowski , 1999
"... We provide a formal framework within which an Information System (IS) could be modelled, analysed, and verified in a compositional manner. Our work is based on Interval Temporal Logic (ITL) and its programming language subset Tempura. This is achieved by considering IS, of an enterprise, as a class ..."
Abstract - Cited by 2 (2 self) - Add to MetaCart
We provide a formal framework within which an Information System (IS) could be modelled, analysed, and verified in a compositional manner. Our work is based on Interval Temporal Logic (ITL) and its programming language subset Tempura. This is achieved by considering IS, of an enterprise, as a class of reactive systems in which it is continually reacting to asynchronously occurring events within a given period of time. Such a reactive nature permits an enterprise to pursue its business activities to best compete with others in the market place. The technique is illustrated by applying it to a small case study from Public Service Systems (PSS). Keywords : Information System, Modelling, Lean Formal methods, Interval Temporal Logic, Simulation The author wishes to acknowledge the funding received from the U.K. Engineering and Physical Sciences Research Council (EPSRC) through the Research Grant GR/M/02583 19 1 INTRODUCTION There are many important and challenging issues that aris...

ATOM: An Object-Based Formal Method for Real-time Systems

by Hussein Zedan, Antonio Cau, Zhiqiang Chen, Hongji Yang - Annals of Software Engineering , 1999
"... An object based formal method for the development of real-time systems, called ATOM, is presented. The method is an integration of the real-time formal technique TAM (Temporal Agent Model) with an industry-strength structured methodology known as HRT-HOOD. ATOM is a systematic formal approach based ..."
Abstract - Cited by 2 (0 self) - Add to MetaCart
An object based formal method for the development of real-time systems, called ATOM, is presented. The method is an integration of the real-time formal technique TAM (Temporal Agent Model) with an industry-strength structured methodology known as HRT-HOOD. ATOM is a systematic formal approach based on the refinement calculus. Within ATOM, a formal specification (or abstract description statement) contains Interval Temporal Logic (ITL) description of the timing, functional, and communication behavior of the proposed real-time system. This formal specification can be analyzed and then refined into concrete statements through successive applications of sound refinement laws. Both abstract and concrete statements are allowed to freely intermix. The semantics of the concrete statements in ATOM are defined denotationally in specification-oriented style using ITL. keywords: object-based, wide-spectrum language, refinement calculus, Temporal Agent Model, HRT-HOOD, Interval Temporal Logic ii ...
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Fractional Permissions and Non-Deterministic Evaluators in Interval Temporal Logic

by Brijesh Dongol, John Derrick, Ian J. Hayes, Stephan Merz, Tiziana Margaria, Julia Padberg, Gabriele Taentzer, Brijesh Dongol, John Derrick, Ian J. Hayes
"... 12th International Workshop on ..."
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12th International Workshop on
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A Framework For Analysing The Effect Of `Change' In Legacy Code

by Shikun Zhou, Hussein Zedan, Antonio Cau, The Gateway, Leicester Le Bh - Proc. of 15th IEEE Int'l Conference on Software Maintenance (ICSM '99
"... We propose a sound and practical approach, based on a formal method (known as Interval Temporal Logic), to cope with `change' and analyse its effect. The approach allows us to capture a snapshot of system's behaviour over which various interesting properties, such as liveness, timeliness a ..."
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We propose a sound and practical approach, based on a formal method (known as Interval Temporal Logic), to cope with `change' and analyse its effect. The approach allows us to capture a snapshot of system's behaviour over which various interesting properties, such as liveness, timeliness and safety properties, can be validated compositionally. These properties may include invariants that are required to be valid after changes have taken place. We also present and evaluate the design and implementation of a formal tool, AnaTempura, which supports the developed approach. A case study is presented to illustrate our approach and the tool. 1. Introduction Computing systems, both hardware and software, are continually evolving. This evolution will inevitably lead to their rapid growth in size and change to their original requirements rendering them to `legacy' status. In fact, some consider a system to be in a legacy state even before it is being deployed! The evolution of software system...
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