A formalism for the specification of multiagent systems should be expressive and illustrative enough to model not only the behavior of one single agent, but also the collaboration among several agents and the influences caused by external events from the environment. For this, state machines [25] seem to provide an adequate means. Furthermore, it should be easily possible to obtain an implementation for each agent automatically from this specification. Last but not least, it is desirable to be able to check whether the multiagent system satisfies some interesting properties. Therefore, the formalism should also allow for the verification or formal analysis of multiagent systems, e.g. by model checking [6]. In this paper, a framework is introduced, which allows us to express declarative aspects of multiagent systems by means of (classical) propositional logic and procedural aspects of these systems by means of state machines (statecharts). Nowadays statecharts are a well accepted means to specify dynamic behavior of software systems. They are a part of the Unified Modeling Language (UML). We describe in a rigorously formal manner, how the specification of spatial knowledge and robot interaction and its verification by model checking can be done, integrating different methods from the field of artificial intelligence such as qualitative (spatial) reasoning and the situation calculus. As example application domain, we will consider robotic soccer, see also [24, 31], which present predecessor work towards a formal logic-based approach for agents engineering.

Abstract Current efforts in Semantic Web Services do not sufficiently address the industrial developments of SOA technology in regards to bottom-up modeling of services, that is, building incremental layers on top of existing service descriptions. An important step in this direction has been made in the W3C by the SAWSDL WG proposing a framework for annotating WSDL services with arbitrary semantic descriptions. We build on the SAWSDL layer and define WSMO-Lite service ontology, narrowing down the use of SAWSDL as an annotation mechanism for WSMO-Lite. Ultimately, our goal is to allow incremental steps on top of existing service descriptions, enhancing existing SOA capabilities with intelligent and automated integration. 1

BPEL is presently the most prominent language to specify and execute business processes, using Web Services as its technological basis. Particular problems arise when activities are faulty: faults have to be propagated, other activities have to be irregularly terminated, etc. We describe

Abstract. We formally define an abstract executable semantics for the Business Process Execution Language for Web Services in terms of a distributed ASM. The goal of this work is to support the design and standardization of the language. “There is a need for formalism. It will allow us to not only reason about the current specification and related issues, but also uncover issues that would otherwise go unnoticed. Empirical deduction is not sufficient. ” – Issue #42, OASIS WSBPEL TC. The language definition assumes an infrastructure for running Web services on some asynchronous communication architecture. A business process is built on top of a collection of Web services performing continuous interactions with the outside world by sending and receiving messages over a communication network. The underlying execution model is characterized by its concurrent and reactive behavior making it particularly difficult to predict dynamic system properties with a sufficient degree of detail and precision under all circumstances. 1

Some of the success stories of model based refinement are recalled, as well as some of the annoyances that arise when refinement is deployed in the engineering of large systems. The way that retrenchment attempts to alleviate such inconveniences is briefly reviewed. The Mondex Electronic Purse formal development provides a highly credible testbed for examining how real world refinement difficulties can be treated via retrenchment. The contributions of retrenchment to integrating the real implementation with the formal development are surveyed, and the extraction of commonly occurring `retrenchment patterns' is recalled. One of the Mondex difficulties, the `Balance Enquiry Quandary' is treated in detail, and the way that retrenchment is able to account for the system behaviour is explained. The problem is reconsidered using generalised forward refinement, and the simplicity of the resolution of the quandary, both by retrenchment, and by generalised forward refinement, inspires the creation of a genuine (1; 1) forward refinement for Mondex, something long thought impossible. The forward treatment exhibits a similar balance enquiry quandary to the backward refinement, as it must, given that both are refinements of an atomic action to a non-atomic protocol, and the forward quandary is dealt with as easily by retrenchment as is the backward case.

Abstract. Building ground models is one of the three constituents of the engineering method for computer-based systems which is known as Abstract State Machine (ASM) method [16]. In this note we characterize ground models, whose epistemological role for a foundation of system design resembles the one Aristotle assigned to axioms to ground science in reality, avoiding infinite regress. We explain how ASM ground models help to resolve two major problems of requirements engineering, providing means a) to obtain for complex computer-based systems an adequate understanding by humans, and b) to cope with ever-changing requirements by faithfully capturing and tracing them via well-documented modeling–for–change. We point out that via an appropriate refinement method one can relate ground models to executable code. 1 IINTRODUCTION In a recent paper [6] Daniel Berry identifies requirements engineering as the main source for “the inevitable pain of software development”, explaining “why there

Abstract. We consider modelling indispensable for the development of complex systems. Modelling must be carried out in a formal notation to reason and make meaningful conjectures about a model. But formal modelling of complex systems is a difficult task. Even when theorem provers improve further and get more powerful, modelling will remain difficult. The reason for this that modelling is an exploratory activity that requires ingenuity in order to arrive at a meaningful model. We are aware that automated theorem provers can discharge most of the onerous trivial proof obligations that appear when modelling systems. In this article we present a modelling tool that seamlessly integrates modelling and proving similar to what is offered today in modern integrated development environments for programming. The tool is extensible and configurable so that it can be adapted more easily to different application domains and development methods. 1

We study reduction congruence, a popular notion of process equality, for the asynchronous π-calculus with timers, and derive several alternative characterisations, one of them being a labelled asynchronous bisimilarity. These results are adapted to an asynchronous π-calculus with timers, locations and message failure. In addition we investigate the problem of how to distribute value-passing processes in a semantics-preserving way.

Semantic Web Services frameworks like OWL-S and WSMO combine semantic descriptions of Web service capabilities, inputs, outputs and behavior with the syntactic interface descriptions in WSDL and XML Schema. The glue between the semantic and syntactic description layers is called grounding. In this paper we identify the uses for grounding and we present the existing grounding approaches and propose new ones, discussing their respective advantages and drawbacks. Finally, we compare OWLS and WSMO with regards to their support of the presented grounding approaches and we recommend which approaches should be considered for future work.

We propose a structured mathematical definition of the semantics of C# programs to provide a platform-independent interpreter view of the language for the C# programmer, which can also be used for a precise analysis of the ECMA [22] standard of the language and as a reference model for teaching. The definition takes care to reflect directly and faithfully -- as much as possible without becoming inconsistent or incomplete -- the descriptions in the C# standard to become comparable with the corresponding models for Java in [37] and to provide for implementors the possibility to check their basic design decisions against an accurate highlevel model. The model sheds light on some of the dark corners of C# and on some critical differences between the ECMA standard and the implementations of the language.