Detail

Inspection Points and Meta-Abduction in Logic Programs

In the context of abduction in Logic Programs, when ?nding an abductive solution for a query, one may want to check too whether some other literals become true (or false) strictly within the abductive solution found, but without performing additional abductions, and without having to produce a complete model to do so. That is, such literals may consume, but not produce, the abduced literals in the solution. We show how this type of reasoning requires a new mechanism, not provided by others already available. To achieve it, we present the concept of Inspection Point in Abductive Logic Programs, and show how, by means of examples, one can employ it to investigate side-effects of interest (the inspection points) in order to help choose among abductive solutions, to express intentions, to implement deontic veri?ers, to code strict preferences, as well as to permit use of passive integrity constraints – i.e. those not allowed to abduce in order to be satis?ed but just to check for satisfaction without further abduction. The touchstone of Inspection Points can be construed as a form of meta-abduction, by meta-abducing an abduction to check (i.e. passively verify) that a certain concrete abduction is indeed adopted in an otherwise purported abductive solution. We furthermore show how to implement it on top of an already existing abduction solving system — ABDUAL — in a way that can be adopted by other systems too.

Seminar Slides: [url]http://centria.di.fct.unl.pt/~lmp/publications/slides/centria08/inspection_points.pdf[/url]