The formalization of abductive reasoning has received increasing attention from logicians. However, few work is found beyond abduction in propositional logic, given that in a first order formalism, the undecidability problem naturally appears, and therefore an abductive problem cannot even be appropriately formulated. Still, many applications in artificial intelligence allow finite domains to work with, and this gives an opportunity to apply abduction in first order logic with restricted domains. In this paper, we present an approach to abductive reasoning in (...) C-structures, first order structures with a finite domain in which each of its elements has a corresponding constant representing its interpretation. By using semantic tableaux with bounded depth, that is, C-tableaux (a modification of N-tableaux, introduced by the authors in previous papers) and δ-resolution calculus, we build an effective procedure for the searching of minimal abductive solutions within the proposed semantics. (shrink)

Abductive problems have been widely studied in propositional logic. First order abduction, however, has been viewed as intractable, for the undecidability of logical consequence. In this paper, we propose a notion of abductive problem, N-abductive problem, which is relative to the cardinality of the minimal model satisfying the given theory. We use a notion of restricted satisfaction, also relative to a domain cardinality. Finally, we propose an effective procedure for the searching of abductive solutions, by means of a modification of (...) Beth's tableaux. (shrink)