# Semantisches Browsen

Abstract Unification in Description Logics has been … Unification in Description Logics has been proposed as an inference service that can, for example, be used to detect redundancies in ontologies. For the Description Logic EL, which is used to define several large biomedical ontologies, unification is NP-complete. An NP unification algorithm for EL based on a translation into propositional satisfiability (SAT) has recently been presented. In this report, we extend this SAT encoding in two directions: on the one hand, we add general concept inclusion axioms, and on the other hand, we add role hierarchies (H) and transitive roles (R+). For the translation to be complete, however, the ontology needs to satisfy a certain cycle restriction. The SAT translation depends on a new rewriting-based characterization of subsumption w.r.t. ELHR+-ontologies.on of subsumption w.r.t. ELHR+-ontologies.  + 12-02  + , , @techreport{ BaBM-LTCS-12-02,  address = {Dresden, Germany},  author = {Franz {Baader} and Stefan {Borgwardt} and Barbara {Morawska}},  institution = {Chair for Automata Theory, Institute for Theoretical Computer Science, Technische Universit{\"a}t Dresden},  note = {See http://lat.inf.tu-dresden.de/research/reports.html.},  number = {12-02},  title = {{SAT} Encoding of Unification in {$\mathcal{ELH}_{R^+}$} w.r.t. Cycle-Restricted Ontologies},  type = {LTCS-Report},  year = {2012},} Techreport  + BaBM-LTCS-12-02.pdf  + Baader  + Franz  + Chair for Automata Theory, Institute for Theoretical Computer Science, Technische Universität Dresden  + See http://lat.inf.tu-dresden.de/research/reports.html.  + Franz Baader, Stefan Borgwardt, Barbara Mo … Franz Baader, Stefan Borgwardt, Barbara Morawska