The minimal unsatisfiability-preserving sub-TBoxes（MUPS）of an unsatisfiable class C identified by two equivalent transformations,axiom splitting and ontology reduction,and three discrimination rules comprise minimal sets of axioms which support the unsatisfiability.Discrimination rules classify all MUPS into three types based on the transitivity of unsatisfiability,fully dependent on C（MUPSf）,transitively dependent on C（MUPSt）and uncertainly dependent on C（MUPSu）.The results show that the number of MUPSt is frequently a large fraction of the total number of all MUPS,but only MUPSf catches the root error of C.Modelers and domain experts conduct iterative repair work effectively,considering only MUPSf in each iteration.The classification shows the significance for the evaluation of the quality of ontologies from the perspective of maintenance and for repair work.
