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- Revision based total semantics for extended normal logic programsPublication . Abrantes, Mário; Pereira, Luís Moniz; Rocha, Isabel OitavemThe purpose of this thesis is the development of a formal semantical approach for extended normal logic programs, where contradictions are tackled by means of a reduction ad absurdum with respect to default negation mechanism, in the fashion of arti cial intelligence belief revision, that leads to a set of implicit revisions. We ful lled these objectives in two steps. The rst one was the implementation of a total paraconsistent models semantics for extended normal logic programs MHP , that combines the merits of two already existing semantics: it inherits the existence property of the abductive minimal hypotheses semantics MH, a semantics of total models, and the property of detection of support on contradiction of the paraconsistent well-founded semantics with explicit negation WFSXP , a semantics of partial paraconsistent models. As for the second step, we developed a revision procedure for inconsistent constrained theories, that tackles inconsistencies arising from contradictions with respect to explicit negation, i.e., L and :L in the same model, and stepping beyond, also tackles inconsistencies arising in more general constrained theories (i.e., theories containing constraints of the type ? A; not B, where A is a conjunction of objective literals and not B stands for a conjunction of default literals). An algorithm for inconsistency propagation detection was also developed. A characterization of the MHP with respect to the semantic formal properties of relevance and cumulativity is furnished, by resorting to a set of results that arose from a detailed study of these properties for a class of 2-valued conservative extensions of the stable models semantics.