The use of typed lambda calculus for comprehension and construction of simulation models in the domain of ecology

We are concerned with two important issues in simulation modelling: model comprehension and model construction. Model comprehension is limited because many important choices taken during the modelling process are not documented. This makes it difficult for models to be modified or used by others. A key factor hindering model construction is the vast modelling search space which must be navigated. This is exacerbated by the fact that many modellers are unfamiliar with the terms and concepts catered to by current tools. The root of both problems is the lack of facilities for representing or reasoning about domain concepts in current simulation technology. The basis for our achievements in both of these areas is the development of a language with two distinct levels; one for representing domain information, and the other for representing the simulation model. Of equal importance, is the fact that we make formal connections between these two levels. The domain we are concerned with is ecological modelling. This language, called Elklogic, is based on the typed lambda calculus. Important features include a rich type structure, the use of various higher order functions, and semantics. This enables complex expressions to be constructed from relatively few primitives. The meaning of each expression can be determined in terms of the domain, the simulation model, or the relationship between the two. We describe a novel representation for sets and substructure, and a variety of other general concepts that are especially useful in the ecological domain. We use the type structure in a novel way: for controlling the modelling search space, rather than a proof search space. We facilitate model comprehension by representing modelling decisions that are embodied in the simulation model. We represent the simulation model separately from, but in terms of a domain mode. The explicit links between the two models constitute the modelling decisions. The semantics of Elklogic enables English text to be generated to explain the simulation model in domain terms

Virtualizing Monitoring and Control Systems: First Operational Experience and Future Applications

Virtualization is a technology that allows emulating a complete computer platform. The potential use ranges from consolidating hardware to running several different operating systems in parallel on one computer to preserving the operability of heritage software. GSOC has been investigating the possibilities of virtualization for some time. Aside from the usual approach of virtualizing the central servers out of administrational, consolidational reasons, the possibilities and advantages of control room client virtualization was explored. While moving mainstream in other businesses, the space community is cautious to apply this technique to the mission critical monitoring and control systems. This paper illustrates three virtualization steps that are underway at GSOC and presents the experiences gained

Representation of Semantic Mappings

The aim of this breakout session was to chart the landscape of existing approaches for representing mappings between heterogeneous models, identify common ideas and formulate research questions to be addressed in the future. In the session, the discussion mainly concerned three aspects: The nature of mappings, existing proposals for mappings and open research questions

Infrastructure for Semantic Interoperability and Integration: Breakout Discussion Summary

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Architectures for Semantic Integration

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An ontological approach to logistics

In today’s global market, the competitiveness of enterprises is strongly dictated by their ability to collaborate with other enterprises. Ontologies enable common understanding of concepts and have been acknowledged as a powerful means to foster collaboration, both within the boundaries of an individual enterprise (intra-enterprise) as outside these boundaries (inter-enterprise). This paper argues that the use of ontologies can be beneficial for enterprise interoperability in the logistics domain, to improve communication and foster knowledge reuse, to facilitate the integration of existing systems and to support the development process of software solutions. Our experience shows that the development of ontologies for logistics is not a trivial task, and guidelines and best practices are necessary in this domain, especially to bridge the gap between theory and practice. On the one hand, proper theoretical and methodological support for ontology engineering is necessary in order to deliver precise, consistent and well-founded solutions to the market. On the other hand, solutions to practical issues should be provided and not take too long to be produced in order not to be detached from the original real market needs. This paper proposes an ontological approach for logistics that balances the trade-off between precision and pragmatism, by combining top-down and bottom-up practices for ontology engineering. From a top-down perspective, we promote the reuse of existing general-purpose (upper) ontologies and specialize them for the purpose of logistics. From a bottom-up perspective, we reuse code lists and classifications that already exist in logistics to support the creation of instances of our upper level concepts. The paper also presents a representative fragment of our core ontology for logistics and identifies areas for further work in ontology engineering for logistics

Winnowing ontologies based on application use

The requirements of specific applications and services are often over estimated when ontologies are reused or built. This sometimes results in many ontologies being too large for their intended purposes. It is not uncommon that when applications and services are deployed over an ontology, only a few parts of the ontology are queried and used. Identifying which parts of an ontology are being used could be helpful to winnow the ontology, i.e., simplify or shrink the ontology to smaller, more fit for purpose size. Some approaches to handle this problem have already been suggested in the literature. However, none of that work showed how ontology-based applications can be used in the ontology-resizing process, or how they might be affected by it. This paper presents a study on the use of the AKT Reference Ontology by a number of applications and services,and investigates the possibility of relying on this usage information to winnow that ontology