Constructing Refinement Operators by Decomposing Logical Implication. - Shan-Hwei Nienhuys-Cheng; Patrick R. J. van der Laag; Leendert W. N. van der Torre (AI*IA, 1993)

Subsumption and Refinement in Model Inference. - Patrick R. J. van der Laag; Shan-Hwei Nienhuys-Cheng (ECML, 1993)

Existence and Nonexistence of Complete Refinement Operators. - Patrick R. J. van der Laag; Shan-Hwei Nienhuys-Cheng (ECML, 1994)

Completeness and Properness of Refinement Operators in Inductive Logic Programming. - Patrick R. J. van der Laag; Shan-Hwei Nienhuys-Cheng (J. Log. Program., 1998)