Debugging EL+ ontologies through horn MUS enumeration

In description logics (DLs), axiom pinpointing refers to the problem of enumerating the minimal subsets of axioms from an ontology that entail a given consequence. Recent developments on axiom pinpointing for the light-weight DL EL+ are based on translating this problem into the enumeration of all minimally unsatisfiable subformulas (MUSes) of a propositional formula, and using advanced SAT-based techniques for solving it. Further optimizations have been obtained by targeting the MUS enumerator to the specific properties of the formula obtained. In this paper we describe different improvements that have been considered since the translation was first proposed. Through an empirical study, we analyse the behaviour of these techniques and how it depends on different characteristics of the original pinpointing problem, and the translated SAT formula.