Active objects have their own thread of control and passive objects are controlled by others. In Object-Z, all objects are modelled as passive objects. Timed Communicating Object Z (TCOZ) extends the Object-Z notation with Timed CSP’s process and timing constructs. The blending of the concepts of object and non-terminating process leads to the notion of active object in TCOZ. This paper conside...

This paper presents a formal framework for modelling and analysing mobile systems. The framework comprises a collection of models of the dominant design paradigms which are readily extended to incorporate details of particular technologies, i.e., programming languages and their run-time support, and applications. The modelling language is Object-Z, an extension of the well-known Z specification...

In this article, we consider the uniqueness of the difference monomials $f^{n}(z)f(z+c)$. Suppose that $f(z)$ and $g(z)$ are transcendental meromorphic functions with finite order and $E_k(1, f^{n}(z)f(z+c))=E_k(1, g^{n}(z)g(z+c))$. Then we prove that if one of the following holds (i) $n geq 14$ and $kgeq 3$, (ii) $n geq 16$ and $k=2$, (iii) $n geq 22$ and $k=1$, then $f(z)equiv t_1g(z)$ or $f(...

This paper presents a minimal and complete set of structural refactoring rules for the Object-Z specification language that allow for the derivation of arbitrary object-oriented architectures. The rules are equivalence preserving and work in concert with existing class refinement theory, so that any design derived using the rule set can be shown to be equivalent to, or a refinement of, the orig...

Object-Z is strong in modeling the data and operations of complex systems. However, it is weak in specifying real-time and concurrent systems. The Timed Communicating Object-Z (TCOZ) extends Object-Z notation with Timed CSP's constructs. TCOZ is particularly well suited for specifying complex systems whose components have their own thread of control. This paper demonstrates expressiveness of th...