37 research outputs found

    Representing time and space for the semantic web

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    Representation of temporal and spatial information for the Semantic Web often involves qualitative defined information (i.e., information described using natural language terms such as "before" or "overlaps") since precise dates or coordinates are not always available. This work proposes several temporal representations for time points and intervals and spatial topological representations in ontologies by means of OWL properties and reasoning rules in SWRL. All representations are fully compliant with existing Semantic Web standards and W3C recommendations. Although qualitative representations for temporal interval and point relations and spatial topological relations exist, this is the first work proposing representations combining qualitative and quantitative information for the Semantic Web. In addition to this, several existing and proposed approaches are compared using different reasoners and experimental results are presented in detail. The proposed approach is applied to topological relations (RCC5 and RCC8) supporting both qualitative and quantitative (i.e., using coordinates) spatial relations. Experimental results illustrate that reasoning performance differs greatly between different representations and reasoners. To the best of our knowledge, this is the first such experimental evaluation of both qualitative and quantitative Semantic Web temporal and spatial representations. In addition to the above, querying performance using SPARQL is evaluated. Evaluation results demonstrate that extracting qualitative relations from quantitative representations using reasoning rules and querying qualitative relations instead of directly querying quantitative representations increases performance at query time

    A survey of qualitative spatial representations

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    Representation and reasoning with qualitative spatial relations is an important problem in artificial intelligence and has wide applications in the fields of geographic information system, computer vision, autonomous robot navigation, natural language understanding, spatial databases and so on. The reasons for this interest in using qualitative spatial relations include cognitive comprehensibility, efficiency and computational facility. This paper summarizes progress in qualitative spatial representation by describing key calculi representing different types of spatial relationships. The paper concludes with a discussion of current research and glimpse of future work

    Spatial ontologies for detecting abnormal maritime behaviour

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    International audienceThe upsurge in piracy and the impact of recent environmental disasters have highlighted the need to improve maritime surveillance. Governmental and private initiatives have developed monitoring systems with improved acquisition and analysis capabilities. These systems rely on one major component, namely the detection of abnormal ship behaviour. This implies a detailed formalisation of expert knowledge. However, the quantity of data, the complexity of situations, the failure to take into account their spatial characteristics and the potential for the same scenario to be interpreted in different ways have proved to be significant problems. We therefore propose a new prototype for the analysis of abnormal ship behaviour. The system is based on a spatial ontology associated with a geographical inference engine. It automatically identifies suspicious vessels and associates them with probable behaviours defined by operational staff

    Enhanced Place Name Search Using Semantic Gazetteers

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    With the increased availability of geospatial data and efficient geo-referencing services, people are now more likely to engage in geospatial searches for information on the Web. Searching by address is supported by geocoding which converts an address to a geographic coordinate. Addresses are one form of geospatial referencing that are relatively well understood and easy for people to use, but place names are generally the most intuitive natural language expressions that people use for locations. This thesis presents an approach, for enhancing place name searches with a geo-ontology and a semantically enabled gazetteer. This approach investigates the extension of general spatial relationships to domain specific semantically rich concepts and spatial relationships. Hydrography is selected as the domain, and the thesis investigates the specification of semantic relationships between hydrographic features as functions of spatial relationships between their footprints. A Gazetteer Ontology (GazOntology) based on ISO Standards is developed to associate a feature with a Spatial Reference. The Spatial Reference can be a GeoIdentifier which is a text based representation of a feature usually a place name or zip code or the spatial reference can be a Geometry representation which is a spatial footprint of the feature. A Hydrological Features Ontology (HydroOntology) is developed to model canonical forms of hydrological features and their hydrological relationships. The classes modelled are endurant classes modelled in foundational ontologies such as DOLCE. Semantics of these relationships in a hydrological context are specified in a HydroOntology. The HydroOntology and GazOntology can be viewed as the semantic schema for the HydroGazetteer. The HydroGazetteer was developed as an RDF triplestore and populated with instances of named hydrographic features from the National Hydrography Dataset (NHD) for several watersheds in the state of Maine. In order to determine what instances of surface hydrology features participate in the specified semantic relationships, information was obtained through spatial analysis of the National Hydrography Dataset (NHD), the NHDPlus data set and the Geographic Names Information System (GNIS). The 9 intersection model between point, line, directed line, and region geometries which identifies sets of relationship between geometries independent of what these geometries represent in the world provided the basis for identifying semantic relationships between the canonical hydrographic feature types. The developed ontologies enable the HydroGazetteer to answer different categories of queries, namely place name queries involving the taxonomy of feature types, queries on relations between named places, and place name queries with reasoning. A simple user interface to select a hydrological relationship and a hydrological feature name was developed and the results are displayed on a USGS topographic base map. The approach demonstrates that spatial semantics can provide effective query disambiguation and more targeted spatial queries between named places based on relationships such as upstream, downstream, or flows through

    Contributions for the exploitation of Semantic Technologies in Industry 4.0

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    120 p.En este trabajo de investigación se promueve la utilización de las tecnologías semánticas, en el entorno de la Industria 4.0, a través de tres contribuciones enfocadas en temas correspondientes a la fabricación inteligente: las descripciones enriquecidas de componentes, la visualización y el análisis de los datos, y la implementación de la Industria 4.0 en PyMEs.La primera contribución es una ontología llamada ExtruOnt, la cual contiene descripciones semánticas de un tipo de máquina de fabricación (la extrusora). En esta ontología se describen los componentes, sus conexiones espaciales, sus características, sus representaciones en tres dimensiones y, finalmente, los sensores utilizados para capturar los datos. La segunda contribución corresponde a un sistema de consulta visual en el cual se utiliza la ontología ExtruOnt y una representación en 2D de la extrusora para facilitar a los expertos de dominio la visualización y la extracción de conocimiento sobre el proceso de fabricación de una manera rápida y sencilla. La tercera contribución consiste en una metodología para la implementación de la Industria 4.0 en PyMEs, orientada al ciclo de vida del cliente y potenciada por el uso de tecnologías Semánticas y tecnologías de renderizado 3D.Las contribuciones han sido desarrolladas, aplicadas y validadas bajo un escenario de fabricación real

    Engineering Temporal and Spatial Aspects in OWL using Patterns

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    WWW is a huge, open, heterogeneous system, however its contents data is mainly human oriented. The Semantic Web needs to assure that data is readable and “understandable” to intelligent software agents, though the use of explicit and formal semantics. Ontologies constitute a privileged artifact for capturing the semantic of the WWW data. Temporal and spatial dimensions are transversal to the generality of knowledge domains and therefore are fundamental for the reasoning process of software agents. Representing temporal/spatial evolution of concepts and their relations in OWL (W3C standard for ontologies) it is not straightforward. Although proposed several strategies to tackle this problem but there is still no formal and standard approach. This work main goal consists of development of methods/tools to support the engineering of temporal and spatial aspects in intelligent systems through the use of OWL ontologies. An existing method for ontology engineering, Fonte was used as framework for the development of this work. As main contributions of this work Fonte was re-engineered in order to: i) support the spatial dimension; ii) work with OWL Ontologies; iii) and support the application of Ontology Design Patterns. Finally, the capabilities of the proposed approach were demonstrated by engineering time and space in a demo ontology about football.A World WideWeb (WWW) é uma rede de dados enorme, aberta, muito rica, heterogénea e não controlada. Contudo, os dados existentes na rede são principalmente orientados ao consumo humano. A Semantic Web, de acordo com a perspectiva de Berners-Lee, deve fornecer condições para que a informação publicada seja lida e interpretada/compreendida por máquinas (agentes), através do enriquecimento semântico formal e explícito. As ontologias são a especificação formal de uma conceptualização partilhada e como tal constituem um artefacto privilegiado para capturar a semântica de um modelo. O formato standard proposto pela W3C (World Wide Web Consortium) para a representação de ontologias no contexto da WWW é o OWL (Web Ontology Language). As dimensões temporal e espacial são transversais à generalidade dos domínios. No processo de entendimento e raciocínio por agentes é crucial a consideração das dimensões temporal e espacial, em particular em tarefas como a análise de narrativas, contextualização, processamento de língua natural ou planeamento. Por exemplo, uma pessoa pode desempenhar vários papéis numa organização no decorrer do tempo; um objecto passa por diversas fases durante o processo de fabrico; ou o planeamento de uma viagem à Europa deve obedecer a diversas restrições temporais e espaciais. Apesar de os humanos demonstrarem uma capacidade inata para lidar com o tempo e o espaço, os agentes inteligentes de software precisam de especificações formais. Contudo, apesar da vasta investigação que tem sido levada a cabo no domínio da engenharia temporal/espacial esta é ainda uma tarefa complexa, trabalhosa e sujeita a erros, visto que é necessário ter conhecimento específico sobre o domínio a modelar e também sobre as teorias que modelam/capturam o tempo e o espaço. Integrar as dimensões temporal e espacial em sistemas inteligentes é uma tarefa complexa e propensa a erros, principalmente porque: 1. muitas vezes o Engenheiro de Conhecimento tem uma percepção intuitiva e informal do tempo e do espaço, enquanto os modelos existentes são formais e complexos, resultando em sistemas nos quais não é possível explorar adequadamente estas dimensões; 2. as dimensões extra, resultantes das componentes temporal e espacial, tornam a ontologia mais complexa, aumentando a dificuldade do processo de verificação e a garantia da completude e consistência do sistema; 3. diferentes intervenientes têm diferentes percepções do tempo e do espaço. Em particular, representar e raciocinar sobre a evolução temporal de conceitos e suas relações considerando ontologias em OWL enfrenta problemas adicionais. A linguagem OWL baseia-se na utilização de relações binárias, o que lhe confere enormes vantagens no processamento automático mas que impõe limitações ao nível da expressividade, tornando complexo representar relações que envolvam mais do que dois argumentos (como por exemplo a caracterização temporal ou espacial de relações). A comunidade científica tem estudado várias formas para fazer face a este problema, nomeadamente: 1. extensões da Lógica Descritiva (DL) com operadores temporais e espaciais; 2. extensões do esquema formal do OWL; 3. aplicação de técnicas de gestão de versões permitindo registar o histórico da evolução da ontologia; 4. ou ainda a criação de esquemas mais complexos para a representação da informação como a criação de conceitos auxiliares para simular a existência de relações n-árias. O principal objectivo deste trabalho consistiu no desenvolvimento de métodos e ferramentas capazes de suportar a engenharia de aspectos temporais e espaciais em sistemas inteligentes através da utilização de ontologias codificadas na linguagem OWL. Uma metodologia de engenharia de ontologias existente chamada Fonte foi utilizada como framework no desenvolvimento deste trabalho. Este método foi aplicado com sucesso na engenharia de aspectos temporais em sistemas inteligentes utilizando ontologias no formato F-Logic. O Fonte utiliza uma abordagem de dividir-para-conquistar de forma que a modelação de domínios complexos pode ser realizada através da composição de diferentes ontologias que definem as diferentes categorias de conhecimento envolvidas no domínio. O Fonte foi utilizado na engenharia dos aspectos temporais em ontologias. Como resultado deste trabalho foi realizada a reengenharia do método Fonte de forma a suportar também a dimensão espacial e a aplicação semiautomática de padrões de desenvolvimento de ontologias (PDO). Em particular este trabalho consistiu no desenvolvimento de: 1. uma linguagem de regras que permite a implementação de PDO e a sua aplicação através da metodologia Fonte 2. mecanismos de verificação que garantem a consistência da ontologia de domínio durante o processo de engenharia; 3. mecanismos de criação automática de propostas baseados em algoritmos de pesquisa semântica e estrutural; 4. ferramenta gráfica de suporte ao método Fonte. As capacidades da metodologia e ferramentas propostas e desenvolvidas foram demonstradas através da engenharia temporal e espacial de uma ontologia do domínio do futebol

    Action, Time and Space in Description Logics

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    Description Logics (DLs) are a family of logic-based knowledge representation (KR) formalisms designed to represent and reason about static conceptual knowledge in a semantically well-understood way. On the other hand, standard action formalisms are KR formalisms based on classical logic designed to model and reason about dynamic systems. The largest part of the present work is dedicated to integrating DLs with action formalisms, with the main goal of obtaining decidable action formalisms with an expressiveness significantly beyond propositional. To this end, we offer DL-tailored solutions to the frame and ramification problem. One of the main technical results is that standard reasoning problems about actions (executability and projection), as well as the plan existence problem are decidable if one restricts the logic for describing action pre- and post-conditions and the state of the world to decidable Description Logics. A smaller part of the work is related to decidable extensions of Description Logics with concrete datatypes, most importantly with those allowing to refer to the notions of space and time

    Description Logic for Scene Understanding at the Example of Urban Road Intersections

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    Understanding a natural scene on the basis of external sensors is a task yet to be solved by computer algorithms. The present thesis investigates the suitability of a particular family of explicit, formal representation and reasoning formalisms for this task, which are subsumed under the term Description Logic

    Attack States Identification in a Logical Framework of Communicating Agents

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    A channel is a logical space where agents make announcements publicly. Examples of such objects are forums, wikis and social networks. Several questions arise about the nature of such a statement as well as about the attitude of the agent herself in doing these announcements. Does the agent know whether the statement is true? Is this agent announcing that statement or its opposite in any other channel? Extensions to Dynamic Epistemic Logics have been proposed in the recent past that give account to public announcements. One major limit of these logics is that announcements are always considered truthful. It is however clear that, in real life, incompetent agents may announce false things, while deceitful agents may even announce things they do not believe in. In this thesis, we provide a logical framework, called Multiple Channel Logic (MCL), able to relate true statements, agent beliefs, and announcements on communication channels. We discuss syntax and semantics of this logic and show the behavior of the p
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