From Absolute-Timer to Relative-Countdown: Patterns for Model-Checking

Many specialised formal methods exist for specifying and verifying real-time systems. We propose extending a traditional method in order to model time with a pattern. In order to carry out verification by model-checking, we demonstrate a new instance of a pattern for real-time modelling. The former pattern is useful to carry out verification by theorem proving. The equivalence with the previous version is studied, and interesting properties for model-checking are reviewed. Finally we report on an experimental case-study

Proved Development of the Real-Time Properties of the IEEE 1394 Root Contention Protocol with the Event B Method

We present a model of the IEEE 1394 Root Contention Protocol with a proof of Safety. This model has real-time properties which are expressed in the language of the event B method: first-order classical logic and set theory. Verification is done by proof using the event B method and its prover, we also have a way to model-check models. Refinement is used to describe the studied system at different levels of abstraction: first without time to fix the scheduling of events abstracly, and then with more and more time constraints

Proved Development of the Real-Time Properties of the IEEE 1394 Root Contention Protocol with the Event B Method

International audienceWe present a model of the IEEE 1394 Root Contention Protocol with a proof of Safety. This model has real-time properties which are expressed in the language of the event B method: first-order classical logic and set theory. Verification is done by proof using the event B method and its prover, we also have a way to model-check models. Refinement is used to describe the studied system at different levels of abstraction: first without time to fix the scheduling of events abstracly, and then with more and more time constraints

American Square Dance Vol. 56, No. 11 (Nov. 2001)

Monthly square dance magazine that began publication in 1945

Southern planter

LYRASIS Members and Sloan FoundationCollege of William and Mary, Earl Gregg Swem Librar

Extending Event-B with discrete timing properties

Event-B is a formal language for systems modelling, based on set theory and predicate logic. It has the advantage of mechanized proof, and it is possible to model a system in several levels of abstraction by using refinement. Discrete timing properties are important in many critical systems. However, modelling of timing properties is not directly supported in Event-B. In this work, we identify three main categories of discrete timing properties for trigger response patterns, deadline, delay and expiry. We introduce language constructs for each of these timing properties that augment the Event-B language. We describe how these constructs have been given a semantics in terms of the standard Event-B constructs. To ease the process of using timing properties in a refinement-based development, we introduce patterns for refining the timing constructs that allow timing properties on abstract models to be replaced by timing properties on refined models. The language constructs and refinement patterns are illustrated through some generic examples.We have developed a tool to support our approach. Our tool is a plug-in to the Rodin tool-set for Event-B and automates the translation of timing properties to Event-B as well as the generation of gluing invariants, required to verify the consistency of timing properties refinement. In the end, we demonstrate the practicality of our approach, by going through the modelling and verifying process of two real-time case studies. The main focus will be the usefulness of the timing refinement patterns in a step-wise modelling and verification process of a real-time system