1,721,164 research outputs found
Using Semantic Web Technologies to Support Enhanced Situation Awareness
No full textThe AKTiveSA project is using Semantic Web technologies to support information fusion and enhanced situational awareness in a simulated humanitarian relief scenario. We have developed an application that shows how situational awareness can be supported during humanitarian relief situations; often occurring alongside military conflict. Semantic Web technologies provide new opportunities for harvesting information from numerous, disparate and often heterogeneous information sources and can be used to better support complex knowledge fusion
A formal approach for RDF/S ontology evolution
No full textIn this paper, we consider the problem of ontology evolution in the face of a change operation. We devise a general-purpose algorithm for determining the effects and side-effects of a requested elementary or complex change operation. Our work is inspired by belief revision principles (ie, validity, success and minimal change) and allows us to handle any change operation in a provably rational and consistent manner. To the best of our knowledge, this is the first approach overcoming the limitations of existing solutions, which deal with each change operation on a per-case basis. Additionally, we rely on our general change handling algorithm to implement specialized versions of it, one per desired change operation, in order to compute the equivalent set of effects and side-effects
On RDF/S ontology evolution
No full textThe algorithms dealing with the incorporation of new knowledge in an ontology (ontology evolution) often share a rather standard process of dealing with changes. This process consists of the specification of the language, the determination of the allowed update operations, the identification of the invalidities that could be caused by each such operation, the determination of the various alternatives to deal with each such invalidity, and, finally, some selection mechanism for singling out the “best” of these alternatives. Unfortunately, most ontology evolution algorithms implement these steps using a case-based, ad-hoc methodology, which is cumbersome and error-prone. The first goal of this paper is to present, justify and make explicit the five steps of the process. The second goal is to propose a general framework for ontology change management that captures this process, in effect generalizing the methodology employed by existing tools. The introduction of this framework allows us to devise a whole class of ontology evolution algorithms, which, due to their formal underpinnings, avoid many of the problems exhibited by ad-hoc frameworks. We exploit this framework by implementing a specific ontology evolution algorithm for RDF ontologies as part of the FORTH-ICS Semantic Web Knowledge Middleware (SWKM)
Ontology evolution: a framework and its application to RDF
No full textThe algorithms dealing with the incorporation of new knowledge in an ontology often share a rather standard process of dealing with changes. This process consists of the determination of the allowed change operations, the identification of the inconsistencies that could be caused by each such operation as well as the various alternatives to deal with each such inconsistency, and, finally, some (manual or automatic) selection mechanism that allows the determination of the “best” of these alternatives. Unfortunately, most ontology evolution algorithms implement these steps using a case-based, ad-hoc methodology, which is cumbersome and error-prone. In this paper we propose a general framework for ontology change management that generalizes the methodology employed by existing tools. The introduction of this framework allows us to devise a whole class of ontology evolution algorithms, which, due to their formal underpinnings, avoid many of the problems exhibited by ad-hoc frameworks. We exploit this framework by implementing a specific ontology evolution algorithm for RDF ontologies
Formal foundations for RDF/S KB evolution
No full textThere are ongoing efforts to provide declarative formalisms of integrity constraints over RDF/S data. In this context, addressing the evolution of RDF/S knowledge bases while respecting associated constraints is a challenging issue, yet to receive a formal treatment. We provide a theoretical framework for dealing with both schema and data change requests. We define the notion of a rational change operator as one that satisfies the belief revision principles of Success, Validity and Minimal Change. The semantics of such an operator are subject to customization, by tuning the properties that a rational change should adhere to. We prove some interesting theoretical results and propose a general-purpose algorithm for implementing rational change operators in knowledge bases with integrity constraints, which allows us to handle uniformly any possible change request in a provably rational and consistent manner. Then, we apply our framework to a well-studied RDF/S variant, for which we suggest a specific notion of minimality. For efficiency purposes, we also describe specialized versions of the general evolution algorithm for the RDF/S case, which provably have the same semantics as the general-purpose one for a limited set of (useful in practice) types of change requests.<br/
Is Defeasible Logic Applicable?
Full text linkIn this paper the application of defeasible logic for automated negotiation is investigated. Defeasible logic is flexible enough to be adapted to several possible negotiation strategies, has efficient implementations, and provides a formal basis for analysis (e.g. to explain why a negotiation was not successful). Two case studies, one small and one more comprehensive, will be described and the feasibility of approaches based on defeasible logic will be discussed
*Corresponding author
No full textAbstract: A general web rule (markup) language has several purposes. It may serve as a lingua franca to exchange rules between different systems and tools. It may be used to express derivation rules for enriching web ontologies by adding definitions of derived concepts or for defining data access permissions; to describe and publish the reactive behaviour of a system in the form of reaction rules; and to provide a complete XML-based specification of a software agent. Further uses may arise in novel web applications. In this paper, we consider the problem of how to design a general web rule language that can be used for these and for future emerging purposes. Given the great diversity of rule concepts and existing rule languages, such a language will consist of several overlapping sublanguages that share a common metamodel. The development of this rule metamodel is a difficult conceptualisation and integration problem
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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