Conditional reasoning in logic programming

We introduce a logic programming language which supports hypothetical and counterfactual reasoning. The language is based on a conditional logic which enables to formalize conditional updates of the knowledge base. Due to the presence of integrity constraints, alternative revisions of the knowledge base may result from an update. We develop an abductive semantics which captures different evolutions of the knowledge base. Furthermore, we provide a goal-directed abductive proof procedure to compute the alternative solutions for a goal. We finally analyze our conditional programming language in the context of belief revision theory, and we establish a connection with Nebel's prioritized base revision.