TABDUAL: a tabled abduction system for logic programs. Accepted in IfCoLog Journal of Logics and their Applications. Available from http://goo.gl/lcQGes

Abduction has been on the back burner in logic programming, as abduction can be too difficult to implement, and costly to perform, in particular if abductive solutions are not tabled. On the other hand, current Prolog systems, with their tabling mecha-nisms, are mature enough to facilitate the introduction of tabling abductive solutions (tabled abduction) into them. Our contributions are as follows. First, we conceptualize a tabled abduction technique for abductive normal logic programs, permitting abductive solutions to be reused, from one abductive context to another. The approach is underpinned by the theory of AB-DUAL and relies on a transformation into tabled logic programs. It particularly makes use of the dual transformation of ABDUAL that enables efficiently handling the prob-lem of abduction under negative goals, by introducing dual positive counterparts for them. Second, we realize this tabled abduction technique in TABDUAL, a system im-plemented in XSB Prolog. The implementation poses several challenges to concretely realize the abstract theory of ABDUAL, e.g., by taking care of all varieties of loop