Generalization by absorption of definite clauses

Absorption is one of the so-called inverse resolution operators of Inductive Logic Programming. The paper studies the properties of absorption that make it suitable for incremental generalization of definite clauses using background knowledge represented by a definite program. The soundness and completeness of the operator are established according to Buntine's model of generalization called generalized subsumption. The completeness argument proceeds by viewing absorption as the inversion of SLD-resolution. In addition, some simplifying techniques are introduced for reducing the non-determinism inherent in usual presentations of absorption. The effect of these simplifications on completeness is discussed.