17 research outputs found
Uniform and Modular Sequent Systems for Description Logics
We introduce a framework that allows for the construction of sequent systems for expressive description logics extending ALC. Our framework not only covers a wide array of common description logics, but also allows for sequent systems to be obtained for extensions of description logics with special formulae that we call "role relational axioms." All sequent systems are sound, complete, and possess favorable properties such as height-preserving admissibility of common structural rules and height-preserving invertibility of rules
Tractable approximate deduction for OWL
Acknowledgements This work has been partially supported by the European project Marrying Ontologies and Software Technologies (EU ICT2008-216691), the European project Knowledge Driven Data Exploitation (EU FP7/IAPP2011-286348), the UK EPSRC project WhatIf (EP/J014354/1). The authors thank Prof. Ian Horrocks and Dr. Giorgos Stoilos for their helpful discussion on role subsumptions. The authors thank Rafael S. Gonçalves et al. for providing their hotspots ontologies. The authors also thank BoC-group for providing their ADOxx Metamodelling ontologies.Peer reviewedPostprin
Decidability of SHIQ with Complex Role Inclusion Axioms
Motivated by medical terminology applications, we investigate the decidability of an expressive and prominent DL, SHIQ, extended with role inclusion axioms of the form RoSâT. It is well-known that a naive such extension leads to undecidability, and thus we restrict our attention to axioms of the form RoSâR or SoRâR, which is the most important form of axioms in the applications that motivated this extension. Surprisingly, this extension is still undecidable. However, it turns out that restricting our attention further to acyclic sets of such axioms, we regain decidability. We present a tableau-based decision procedure for this DL and report on its implementation, which behaves well in practise and provides important additional functionality in a medical terminology application
Decidability of SHIQ with Complex Role Inclusion Axioms
Motivated by medical terminology applications, we investigate the decidability of an expressive and prominent DL, SHIQ, extended with role inclusion axioms of the form RoSâT. It is well-known that a naive such extension leads to undecidability, and thus we restrict our attention to axioms of the form RoSâR or SoRâR, which is the most important form of axioms in the applications that motivated this extension. Surprisingly, this extension is still undecidable. However, it turns out that restricting our attention further to acyclic sets of such axioms, we regain decidability. We present a tableau-based decision procedure for this DL and report on its implementation, which behaves well in practise and provides important additional functionality in a medical terminology application
Decidability of SHIQ with Complex Role Inclusion Axioms
Motivated by medical terminology applications, we investigate the decidability of an expressive and prominent DL, SHIQ, extended with role inclusion axioms of the form RoSâT. It is well-known that a naive such extension leads to undecidability, and thus we restrict our attention to axioms of the form RoSâR or SoRâR, which is the most important form of axioms in the applications that motivated this extension. Surprisingly, this extension is still undecidable. However, it turns out that restricting our attention further to acyclic sets of such axioms, we regain decidability. We present a tableau-based decision procedure for this DL and report on its implementation, which behaves well in practise and provides important additional functionality in a medical terminology application
Module extraction for inexpressive description logics
Module extraction is an important reasoning task, aiding in the design, reuse and maintenance
of ontologies. Reasoning services such as subsumption testing and MinA extraction have been
shown to bene t from module extraction methods. Though various syntactic traversal-based
module extraction algorithms exist for extracting modules, many only consider the subsumee
of a subsumption statement as a selection criterion for reducing the axioms in the module.
In this dissertation we extend the bottom-up reachability-based module extraction heuristic
for the inexpressive Description Logic EL, by introducing a top-down version of the heuristic
which utilises the subsumer of a subsumption statement as a selection criterion to minimize
the number of axioms in a module. Then a combined bidirectional heuristic is introduced
which uses both operands of a subsumption statement in order to extract very small modules.
We then investigate the relationship between MinA extraction and bidirectional reachabilitybased
module extraction. We provide empirical evidence that bidirectional reachability-based
module extraction for subsumption entailments in EL provides a signi cant reduction in the
size of modules for almost no additional costs in the running time of the original algorithms.Computer ScienceM. Sc. (Computer Science