1,076 research outputs found
State-of-the-art on evolution and reactivity
This report starts by, in Chapter 1, outlining aspects of querying and updating resources on
the Web and on the Semantic Web, including the development of query and update languages
to be carried out within the Rewerse project.
From this outline, it becomes clear that several existing research areas and topics are of
interest for this work in Rewerse. In the remainder of this report we further present state of
the art surveys in a selection of such areas and topics. More precisely: in Chapter 2 we give
an overview of logics for reasoning about state change and updates; Chapter 3 is devoted to briefly describing existing update languages for the Web, and also for updating logic programs;
in Chapter 4 event-condition-action rules, both in the context of active database systems and
in the context of semistructured data, are surveyed; in Chapter 5 we give an overview of some relevant rule-based agents frameworks
Derivation methods for hybrid knowledge bases with rules and ontologies
Trabalho apresentado no âmbito do Mestrado em Engenharia Informática, como requisito parcial para obtenção do grau de Mestre em Engenharia InformáticaFirst of all, I would like to thank my advisor, José Júlio Alferes, for his incredible support. Right from the start, during the first semester of this work, when we were 2700 km apart and meeting regularly via Skype, until the end of this dissertation, he was always committed and available for discussions, even when he had lots of other urgent things to do.
A really special thanks to Terrance Swift, whom acted as an advisor, helping me a lot in
the second implementation, and correcting all XSB’s and CDF’s bugs. This implementation
wouldn’t surely have reached such a fruitful end without his support.
I would also like to thank all my colleagues and friends at FCT for the great work environment and for not letting me take myself too serious. A special thanks to my colleagues from Dresden for encouraging me to work even when there were so many other interesting things to do as an Erasmus student.
I’m indebted to LuĂs Leal, Bárbara Soares, Jorge Soares and CecĂlia Calado, who kindly
accepted to read a preliminary version of this report and gave me their valuable comments.
For giving me working conditions and a partial financial support, I acknowledge the Departamento de Informática of the Faculdade de Ciências e Tecnologias of Universidade Nova de Lisboa.
Last, but definitely not least, I would like to thank my parents and all my family for their continuous encouragement and motivation. A special thanks to Bruno for his love, support and patience
Promoting Modular Nonmonotonic Logic Programs
Modularity in Logic Programming has gained much attention over the past years. To date, many formalisms have been proposed that feature various aspects of modularity. In this paper, we present our current work on Modular Nonmonotonic Logic Programs (MLPs), which are logic programs under answer set semantics with modules that have contextualized input provided by other modules. Moreover, they allow for (mutually) recursive module calls. We pinpoint issues that are present in such cyclic module systems and highlight how MLPs addresses them
HEX Programs with Action Atoms
HEX programs were originally introduced as a general framework for extending declarative logic programming, under the stable model semantics, with the possibility of bidirectionally accessing external sources of knowledge and/or computation. The original framework, however, does not deal satisfactorily with stateful external environments: the possibility of predictably influencing external environments has thus not yet been considered explicitly. This paper lifts HEX programs to ACTHEX programs: ACTHEX programs introduce the notion of action atoms, which are associated to corresponding functions capable of actually changing the state of external environments. The execution of specific sequences of action atoms can be declaratively programmed. Furthermore, ACTHEX programs allow for selecting preferred actions, building on weights and corresponding cost functions. We introduce syntax and semantics of acthex programs; ACTHEX programs can successfully be exploited as a general purpose language for the declarative implementation of executable specifications, which we illustrate by encodings of knowledge bases updates, action languages, and an agent programming language. A system capable of executing ACTHEX programs has been implemented and is publicly available
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