1,721,022 research outputs found
Qualitative reasoning with a Spatio-Temporal language
No full textIn this paper we present an approach to qualitative spatial reasoning based on the spatio-temporal language STACLP 18. In particular, we show how the topological 9-intersection model 7 and the direction relations based on projections 16 can be modelled in such a framework. STACLP is a constraint logic programming language where formulae can be annotated with labels (annotations) and where relations between these labels can be expressed by using constraints. Annotations are used to represent both time and space
Qualitative Spatial Reasoning in a Logical Framework
No full textIn this paper we present an approach to qualitative spatial reasoning based on the spatio-temporal language STACLP 18. In particular, we show how the topological 9-intersection model 7 and the direction relations based on projections 16 can be modelled in such a framework. STACLP is a constraint logic programming language where formulae can be annotated with labels (annotations) and where relations between these labels can be expressed by using constraints. Annotations are used to represent both time and space
Minimisation of Event Structures
Full text linkEvent structures are fundamental models in concurrency theory, providing a representation of events in computation and of their relations, notably concurrency, conflict and causality. In this paper we present a theory of minimisation for event structures. Working in a class of event structures that generalises many stable event structure models in the literature, (e.g., prime, asymmetric, flow and bundle event structures) we study a notion of behaviour-preserving quotient, taking hereditary history preserving bisimilarity as a reference behavioural equivalence. We show that for any event structure a uniquely determined minimal quotient always exists. We observe that each event structure can be seen as the quotient of a prime event structure, and that quotients of general event structures arise from quotients of (suitably defined) corresponding prime event structures. This gives a special relevance to quotients in the class of prime event structures, which are then studied in detail, providing a characterisation and showing that also prime event structures always admit a unique minimal quotient
Basic theory of F-bounded quantification
Full text linkSystem F-bounded is a second order typed lambda calculus, where the basic features of object-oriented languages can be naturally modelled. F-bounded extends the better known system , in a way that provides an immediate solution for the treatment of the so-called ``binary methods''. Although more powerful than and also quite natural, system F-bounded has only been superficially studied from a foundational perspective and many of its essential properties have been conjectured but never proved in the literature. The aim of this paper is to give a solid foundation to F-bounded, by addressing and proving the key properties of the system. In particular transitivity elimination, completeness of the type checking semi-algorithm, the subject reduction property for reduction, conservativity with respect to system and antisymmetry of a ``full'' subsystem are considered, and various possible formulations for system F-bounded are compared. Finally a semantic interpretation of system F-bounded is presented, based on partial equivalence relations
A Scalable Model for Vessel-Generated Underwater Noise: Enhancing Efficiency through Parallelisation
Full text linkUnderwater noise pollution by shipping activities is widely recognised as a significant threat to marine life. The noise emitted by vessels can have various detrimental effects on fish and marine ecosystems. Therefore, accurately estimating and analysing vessel-generated underwater noise is a critical challenge for the protection and conservation of marine environments. For this reason, we have built a model for the spatio-temporal characterisation of underwater noise generated by vessels. This paper builds on this model by optimising the code pipeline, implementing table partitioning and leveraging parallelisation techniques. These enhancements allow us to explore various partitioning methods while significantly improving the computational performance and enabling more efficient analysis of underwater noise. Our approach not only improves the computational efficiency but also preserves the accuracy of the noise calculations, offering a more scalable solution for large datasets
A logical approach to cooperative information systems
No full text"Cooperative information system management" refers to the capacity of several computing systems to communicate and cooperate in order to acquire, store, manage, query data and knowledge. Current solutions to the problem of cooperative information management are still far from being satisfactory. In particular, they lack the ability to fully model cooperation among heterogeneous systems according to a declarative style. The use of a logical approach to model all aspects of cooperation seems very promising. In this paper, we define a logical language able to support cooperative queries, updates and update propagation. We model the sources of information as deductive databases, sharing the same logical language to express queries and updates, but containing independent, even if possibly related, data. We use the Obj-U-Datalog (E. Bertino, G. Guerrini, D. Montesi, Toward deductive object databases, Theory and Practice of Object Systems 1 (1) (1995) 19-39) language to model queries and transactions in each source of data. Such language is then extended to deal with active rules in the style of Active-U-Datalog (E. Bertino, B. Catania, V. Gervasi, A. Raffaeta, Active-U-Datalog: Integrating active rules in a logical update language, in: B. Freitag, H. Decker, M. Kifer, A. Voronkov (Eds.), LBCS 1472: Transactions and Change in Login Databases, 1998, pp. 106-132), interpreted according to the PARK semantics proposed in G. Gottlob, G. Moerkotte, V.S. Subrahmanian (The PARK semantics for active rules, in: P.M.G. Apers, M. Bouzeghoub, G. Gardarin (Eds.), LNCS 1057: Proceedings of the Fifth International Conference on Extending Database Technology, 1996, pp. 35-55). By using active rules, a system can efficiently perform update propagation among different databases. The result is a logical environment, integrating active and deductive rules, to perform update propagation in a cooperative framework. (C) 2000 Elsevier Science Inc. All rights reserved
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