# Semantisches Browsen

Abstract Unification in Description Logics (DLs) ha … Unification in Description Logics (DLs) has been proposed as an inference service that can, for example, be used to detect redundancies in ontologies. For the DL EL, which is used to define several large biomedical ontologies, unification is NP-complete. A goal-oriented NP unification algorithm for EL that uses nondeterministic rules to transform a given unification problem into solved form has recently been presented. In this report, we extend this goal-oriented algorithm in two directions: on the one hand, we add general concept inclusion axioms (GCIs), and on the other hand, we add role hierarchies (H) and transitive roles (R+). For the algorithm to be complete, however, the ontology consisting of the GCIs and role axioms needs to satisfy a certain cycle restriction.ds to satisfy a certain cycle restriction.  + 12-05  + , , @techreport{ BaBM-LTCS-12-05,  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 = {12-05},  title = {A Goal-Oriented Algorithm for Unification in {$\mathcal{ELH}_{R^+}$} w.r.t. Cycle-Restricted Ontologies},  type = {LTCS-Report},  year = {2012},} Techreport  + BaBM-LTCS-12-05.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