%0 Journal Article %J Semantic Web %D 2013 %T Paraconsistent OWL and Related Logics %A Frederick Maier %A Yue Ma %A Pascal Hitzler %K Automated Deduction %K Complexity %K Description Logic %K OWL %K Paraconsistency %K Semantic Web %K Web Ontology Language %X The Web Ontology Language OWL is currently the most prominent formalism for representing ontologies in Semantic Web applications. OWL is based on description logics, and automated reasoners are used to infer knowledge implicitly present in OWL ontologies. However, because typical description logics obey the classical principle of explosion, reasoning over inconsistent ontologies is impossible in OWL. This is so despite the fact that inconsistencies are bound to occur in many realistic cases, e.g., when multiple ontologies are merged or when ontologies are created by machine learning or data mining tools. In this paper, we present four-valued paraconsistent description logics which can reason over inconsistencies. We focus on logics corresponding to OWL DL and its profiles. We present the logic SROIQ4, showing that it is both sound relative to classical SROIQ and that its embedding into SROIQ is consequence preserving. We also examine paraconsistent varieties of EL++, DL-Lite, and Horn-DLs. The general framework described here has the distinct advantage of allowing classical reasoners to draw sound but nontrivial conclusions from even inconsistent knowledge bases. Truth-value gaps and gluts can also be selectively eliminated from models (by inserting additional axioms into knowledge bases). If gaps but not gluts are eliminated, additional classical conclusions can be drawn without affecting paraconsistency. %B Semantic Web %V 4 %P 395–427 %G eng %U http://dx.doi.org/10.3233/SW-2012-0066 %R 10.3233/SW-2012-0066 %0 Conference Paper %B Proceedings of the 20th International Conference on World Wide Web, WWW 2011, Hyderabad, India, March 28 - April 1, 2011 %D 2011 %T A Better Uncle for OWL: Nominal Schemas for Integrating Rules and Ontologies %A Markus Krötzsch %A Frederick Maier %A Adila Krisnadhi %A Pascal Hitzler %E Sadagopan Srinivasan %E Krithi Ramamritham %E Arun Kumar %E M. P. Ravindra %E Elisa Bertino %E Ravi Kumar %K datalog %K Description Logic %K Semantic Web Rule Language %K SROIQ %K tractability %K Web Ontology Language %X We propose a description-logic style extension of OWL 2 with nominal schemas which can be used like "variable nominal classes" within axioms. This feature allows ontology languages to express arbitrary DL-safe rules (as expressible in SWRL or RIF) in their native syntax. We show that adding nominal schemas to OWL 2 does not increase the worst-case reasoning complexity, and we identify a novel tractable language SROELV3(\cap, x) that is versatile enough to capture the lightweight languages OWL EL and OWL RL. %B Proceedings of the 20th International Conference on World Wide Web, WWW 2011, Hyderabad, India, March 28 - April 1, 2011 %I ACM %P 645-654 %8 03/2011 %@ 978-1-4503-0632-4 %G eng %U http://doi.acm.org/10.1145/1963405.1963496 %R 10.1145/1963405.1963496