Abduction in Well-Founded Semantics and Generalized Stable Models

Abductive logic programming offers a formalism to declaratively express and solve problems in areas such as diagnosis, planning, belief revision and hypothetical reasoning. Tabled logic programming offers a computational mechanism that provides a level of declarativity superior to that of Prolog, and which has supported successful applications in fields such as parsing, program analysis, and model checking. In this paper we show how to use tabled logic programming to evaluate queries to abductive frameworks with integrity constraints when these frameworks contain both default and explicit negation. The result is the ability to compute abduction over well-founded semantics with explicit negation and answer sets. Our approach consists of a transformation and an evaluation method. The transformation adjoins to each objective literal $O$ in a program, an objective literal $not(O)$ along with rules that ensure that $not(O)$ will be true if and only if $O$ is false. We call the resulting program a {\em dual} program. The evaluation method, \wfsmeth, then operates on the dual program. \wfsmeth{} is sound and complete for evaluating queries to abductive frameworks whose entailment method is based on either the well-founded semantics with explicit negation, or on answer sets. Further, \wfsmeth{} is asymptotically as efficient as any known method for either class of problems. In addition, when abduction is not desired, \wfsmeth{} operating on a dual program provides a novel tabling method for evaluating queries to ground extended programs whose complexity and termination properties are similar to those of the best tabling methods for the well-founded semantics. A publicly available meta-interpreter has been developed for \wfsmeth{} using the XSB system.Comment: 48 pages; To appear in Theory and Practice in Logic Programmin

Impact of Clethra arborea Aiton (Clethraceae) in a Special Protection Area of São Miguel Island, Azores.

Clethra arborea Aiton (Clethraceae) is a tree endemic to Madeira Island, and a recent introduction to São Miguel Island at Tronqueira/Pico da Vara, a Special Protection Area (SPA) included in Natura 2000, habitat of the endemic bird Pyrrhula murina Godman (Aves: Fringillidae). In this work the impact of C. arborea on the native vegetation was evaluated. Microhabitats associated with C. arborea and with native trees, and areas with different degrees of infestation by C. arborea were compared for soil pH, soil conductivity, soil macronutrient availability, leaf litter production, number of seedlings and vegetation structure. There were no clear differences in soil pH, conductivity and macronutrient availability, either between micro-habitats associated with C. arborea and with native trees, or between areas with different degrees of infestation by C. arborea. Leaf litter production was significantly higher in micro-habitats associated with C. arborea and higher still in areas with high levels of infestation. The number of seedlings and the percentage of endemic seedlings differed significantly between microhabitats associated with C. arborea and those associated with endemic trees. Invasion by C. arborea modified vegetation structure, especially biovolume, which was much higher in invaded areas. By considerably decreasing the proportion of biovolume allocated to native trees, C. arborea infestations may have a negative impact on the conservation efforts at the SPA

Preferential theory revision

AbstractEmploying a logic program approach, this paper focuses on applying preferential reasoning to theory revision, both by means of preferences among existing theory rules, and by means of preferences on the possible abductive extensions to the theory. And, in particular, how to prefer among plausible abductive explanations justifying observations

Eye gaze in individuals with and without convergence insufficiency

Aims of the study: Characterization of the eye gaze, through the analysis of eye movements during fixation and pursuit of a target in young adults with convergence insufficiency and young adults with normal binocular vision. In the horizontal from left-right in the vertical from up-down, for the most used direction, in the horizontal from right-left, and in the vertical from down-up for the less used direction.info:eu-repo/semantics/publishedVersio

Intervention with self-suggestive procedures for self-efficacy and pain control

Introdução – A dor predomina em muitas patologias médicas e acarreta diversas implicações para o doente. O presente estudo visou avaliar a eficácia de uma intervenção autossugestiva, como complemento ao tratamento médico, no aumento da autoeficácia e controlo da dor. Metodologia – Para a concretização deste objetivo, 205 pacientes adultos com dor foram distribuídos aleatoriamente por dois grupos que se distinguiram quanto à intervenção recebida durante 12 semanas, nomeadamente IAS (intervenção autossugestiva) e ISAS (intervenção sem autossugestão). Os dois grupos foram comparados quanto à evolução da autoeficácia e do controlo da dor ao longo desse período. Resultados e discussão – Os resultados mostraram um aumento estatisticamente significativo destas variáveis no grupo IAS mas não no grupo ISAS, sugerindo a eficácia da intervenção autossugestiva. Este estudo representa, assim, um importante contributo para a prática clínica com os doentes com dor.Introduction – Pain is the predominant complaint in many medical diseases and carries several implications for the patient. The present study aimed to evaluate the effectiveness of a self-suggestive intervention, as a complement to medical treatment, in the patients’ self-efficacy and pain control. Methodology – For this aim, 205 adult patients suffering from pain were randomized in two groups that received different interventions during 12 weeks: IAS group received a self-suggestive intervention and ISAS group received an intervention without self-suggestion. The two groups were compared regarding the changes in self-efficacy and pain control over the 12 weeks. Results and discussion – The results showed a statistically significant increase of these variables in the IAS group but not in the ISAS group, suggesting the efficacy of the self-suggestive intervention. This study represents an important contribution to the clinical practice with patients suffering from pain