In the statistical sampling method, as in any other statistical approaches for measuring software reliability, the inputs to the program are chosen according to the estimated probability with which they occur in field use, forming the operational profile. However, in practice it is very difficult to accurately assess the operational distribution of input points. Furthermore, a variety of factor...

For complex systems of systems, such as those required to perform maritime security, system architects have numerous choices they may select from, both in the components and in the way the system operates. Component choices, such as the length of a wing or the number of ground control stations, are often considered in tradespace studies, but this paper highlights the operational choices that ar...

The deductive veri cation of concurrent programs gained new tools with the advent of Concurrent Separation Logic (CSL). This program logic is a compositional method that combines the Owicki-Gries method with Separation Logic, allowing to reason and prove correct concurrent programs manipulating shared mutable data structure. The soundness of Concurrent Separation Logic had been established usin...

Complex sfotware systems typically involve features like time, concurrency and probability, and probabilistic computations are playing an increasing role. However it is currently challenging to formalize languages incorporating all those features. Recently the language PTSC has been proposed to integrate probability and time with shared-variable concurrency [56, 59], where the operational seman...

Compositional abstractions underly many reasoning principles for concurrent programs: the concurrent environment is abstracted in order to reason about a thread in isolation; and these abstractions are composed to reason about a program consisting of many threads. For instance, separation logic uses formulae that describe part of the state, abstracting the rest; when two threads use disjoint st...

CSP# (Communicating Sequential Programs) is a modelling language designed for specifying concurrent systems by integrating CSP-like compositional operators with sequential programs updating shared variables. In this paper, we define an observation-oriented denotational semantics in an open environment for the CSP# language based on the UTP framework. To deal with shared variables, we lift tradi...

Goossens defined a structural operational semantics for a subset of VHDL-87 and proved that the parallelism present in VHDL is benign. We extend this work to include VHDL-93 features such as shared variables and postponed processes that change the underlying semantic model. In the presence of shared variables, non-deterministic execution of VHDL-93 processes destroys the unique meaning property...

The representation of free variables is crucial for the efficiency of the implementation of various kinds of rewrite systems. We give an innovative, although very natural, representation of variables abstract enough to fit in many different frameworks and more satisfactory from an operational perspective than usual representations. This work also provides a generalisation of director strings fo...

This paper describes our concept of the proper (and improper) use of diagnostic variables in severestorm forecasting. A framework for classification of diagnostic variables is developed, indicating the limitations of such variables and their suitability for operational diagnosis and forecasting. The utility of diagnostic variables as forecast parameters is discussed, in terms of what we conside...

Verilog is a hardware description language (HDL) that has been standardized and widely used in industry. It contains interesting features such as event-driven computation and shared-variable concurrency. This paper considers how the algebraic semantics links with the operational semantics for Verilog. Our approach is to apply the equational and rewriting logic system Maude in exploring the link...