where b ranges over a set BExp of boolean expressions, a ranges over a set Act of basic actions and p is a real number with 0 < p < 1. We write cond(b, P,Q) for the conditional usually denoted as if b then P else Q fi and while(b, P ) for the while loop usually denoted as while b do P od The program P8Q nondeterministically executes either P or Q. The program P p⊕Q executes P with probability p...

In 1979, Cousot and Cousot gave a specification of the “best” (most-precise) abstract transformer possible for a given concrete transformer and a given abstract domain. Unfortunately, their specification does not lead to an algorithm for obtaining best transformers. In fact, algorithms are known for only a few abstract domains. This paper presents a parametric framework that, for some abstract ...

Weak omega algebra and demonic refinement algebra are two ways of describing systems with finite and infinite iteration. We show that these independently introduced kinds of algebras can actually be defined in terms of each other. By defining modal operators on the underlying weak semiring, that result directly gives a demonic refinement algebra of commands. This yields models in which extensio...

Continuous monitoring of Power transformer is very much essential during its operation. Incipient faults inside the tank and winding insulation needs careful attention. Traditional ratio methods and Duval triangle can be employed to diagnose the incipient faults. Many times correct diagnosis due to the borderline problems and the existence of multiple faults may not be possible. Artificial inte...

G. Plotkin and the author [13] have worked out the equivalence between state transformer semantics and predicate transformer semantics in a domain theoretical setting for programs combining nondeterminism and probability. Works of C. Morgan and co-authors [20], Keimel, Rosenbusch and Streicher [14, 15], already go in the same direction using only discrete state spaces. In fact, Keimel and Plotk...

As interest in components and composition-related methods is growing rapidly, it is not always clear what the goals (and the corresponding difficulties) actually are. If composition is to become central in the future of software engineering, we need to better identify the fundamental issues that are related to it, before we attempt to solve them as they occur in object-oriented systems or in co...

This paper describes extensions of the B language concerning control flow breaks in implementations and specification of operations with exceptional behaviors. It does not claim to define those extensions in a pure formal and complete way. It is rather a presentation of what could be done and how it could be done. A syntax is proposed and proof obligations are defined using a weakest preconditi...