Some properties of system descriptions of

J Ucs, 2008

The abstract syntax and static semantics of UML, the widely-used generalpurpose graphical modeling language, have been standardized in a four-layer metamodeling framework. However UML's dynamic semantics, such as UML Precise Action Semantics and the behaviors like activities, interactions and state machines, are only standardized in a natural language-English. It is commonly argued that such informal description inevitably involves ambiguities and lacks rigorousness, precluding the early simulation and reasoning about a UML system design. Here we select Action Semantics (AS) as the vehicle to formalize UML. AS is a mature semantics description framework which has advantages of intelligibility, modularity and practicability. In our approach, we formalize UML indirectly by formalizing its textual correspondent-an extended Action Language, which plays a key role as the interface between UML and its action semantics.

1999

Modularity is an important pragmatic aspect of semantic descriptions: good modularity is needed to allow the reuse of existing descriptions when extending or changing the described language. In denotational semantics, the issue of modularity has received much attention, and appropriate abstractions have been introduced, so that definitions of semantic functions may be independent of the details of how computations are modelled. In structural operational semantics (SOS), however, this issue has largely been neglected, and SOS descriptions of programming languages typically exhibit rather poor modularity; the original SOS given for Action Notation (the notation for the semantic entities used in action semantics) suffered from the same problem. This paper recalls a recent proposal, called MSOS, for obtaining a high degree of modularity in SOS, and presents an MSOS description of Action Notation. Due to its modularity, the MSOS description pin-points some complications in the design of Action Notation, and should facilitate the design of an improved version of the notation. It also provides a major example of the applicability of the MSOS framework. The reader is assumed to be familiar with conventional SOS and with the basic concepts and constructs of Action Notation. The description of Action Notation is formulated almost entirely in Casl, the common algebraic specification language.

Theoretical Computer Science, 2018

In the area of algebraic specification there are two main approaches for defining observational abstraction: behavioural specifications use a notion of observational satisfaction for the axioms of a specification, whereas abstractor specifications define an abstraction from the standard semantics of a specification w.r.t. an observational equivalence relation between algebras. Earlier work by Bidoit, Hennicker, Wirsing has shown that in the case of first-order logic specifications both concepts coincide semantically under mild assumptions. Analogous results have been shown by Sannella and Hofmann for higher-order logic specifications and recently, by Hennicker and Madeira, for specifications of reactive systems using a dynamic logic with binders. In this paper, we bring these results into a common setting: we isolate a small set of characteristic principles to express the behaviour/abstractor equivalence and show that all three mentioned specification frameworks satisfy these principles and therefore their behaviour and abstractor specifications coincide semantically (under mild assumptions). As a new case we consider observational modal logic where observational satisfaction of Hennessy-Milner logic formulae is defined "up to" silent transitions and observational abstraction is defined by weak bisimulation. We show that in this case the behaviour/abstractor equivalence can only be obtained, if we restrict models to weakly deterministic labelled transition systems.

«UML» 2001—The Unified …, 2001

We introduce in this paper an algebra of actions specially tailored to serve as basis of an action-based formalism for writing electronic contracts. The proposed algebra is based on the work on Kleene algebras but does not consider the Kleene star and introduces a new constructor for modelling concurrent actions. The algebraic structure is resource-aware and incorporates special actions called tests. In order to be in accordance with the intuition behind electronic contracts we consider new properties of the algebraic structure, in particular a conflict relation and a demanding partial order. We also study a canonical form of the actions which, among other things, helps to naturally define a notion of action negation. Our action negation is more general than just negation of atomic actions, but more restricted than the negation involving the universal relation. A standard interpretation of the algebra is given in terms of guarded rooted trees with specially defined operations on them. The algebra is proven to be complete over the standard interpretation.

Computational Logic in Multi-Agent Systems, 2004

An important branch of investigation in the field agents has been the definition of high level languages for representing eects of ac- tions, the programs written in such languages being usually called action programs. Logic programming is an important area in the field of knowl- edge representation and some languages for specifying updates of Logic Programs had been defined. In

Systems research and behavioral science, 1980

Lecture Notes in Computer Science, 1994

Action systems are used to extend program refinement meth- ods for sequential programs, as described in the refinement calculus ,t o parallel and reactive system refinement. They provide a general descrip- tion of reactive systems, capable of modeling terminating, possibly abort- ing and infinitely repeating systems. We show how to extend the action system model to refinement of modular systems.

2006

Abstract. Real world applications of action description languages involve systems that have real-time constraints. The occurrence of an action is just as important as the time at which the action occurs. In order to be able to model such real-time systems, the action description language A is extended with real-time clocks and constraints. The formal syntax and semantics of the extended language are defined, and the use of logic programming as a means to an implementation of real-time A is discussed.