In this paper, we present a brief overview of Pellet: a complete OWL-DL reasoner with acceptable to very good performance, extensive iddleware, and a number of unique features. Pellet is the first sound and complete OWL-DL reasoner with extensive support for reasoning ith individuals (including nominal support and conjunctive query), user-defined datatypes, and debugging support for ontologies....

The OWL language [1] is being widely used to define ontologies in the Web. This language provides three increasingly expressive sublanguages, namely OWL Lite, OWL-DL and OWL Full. The OWL-DL XML based syntax together with its correspondence with Description Logics (DL) [2], make it a good candidate to be the standard language for defining ontologies used by Semantic Web applications. However, t...

The Description Logic (DL) research of the last 20 years was mainly concerned with increasing the expressive power of the employed description language without losing the ability of implementing highly-optimized reasoning systems that behave well in practice, in spite of the ever increasing worst-case complexity of the underlying inference problems. OWL DL, the standard ontology language for th...

Scalable query answering over Description Logic (DL) based ontologies plays an important role for the success of the Semantic Web. Towards tackling the scalability problem, we propose a decomposition-based approach to optimizing existing OWL DL reasoners in evaluating conjunctive queries in OWL DL ontologies. The main idea is to decompose a given OWL DL ontology into a set of target ontologies ...

We describe ongoing work on a bidirectional mapping between Attempto Controlled English (ACE) and OWL DL. ACE is a well-studied controlled natural language, with a parser that converts ACE texts into Discourse Representation Structures (DRS). We show how ACE can be translated into OWL DL (by using the DRS as interlingua) and how OWL DL can be verbalized in ACE. This mapping renders ACE an inter...

The database usability experience has shown that visual query languages tend to be superior to textual languages in many aspects. By applying this principle in the context of ontologies, we present GLOO, a graphical query language for OWL-DL ontologies. GLOO maps diagrammatic queries to DL based query languages such as nRQL, which is offered by the OWL-DL reasoner Racer. GLOO hides the complexi...

Description Logics (DLs) are knowledge representation formalisms that provide, for example, the logical underpinning of the W3C OWL standards. Conjunctive queries (CQs), the standard query language in databases, have recently gained significant attention for querying DL knowledge bases. Several different techniques are available for a wide range of DLs. Nevertheless, for OWL 1 DL and OWL 2 DL, ...

We present OWL-log, which is an implementation of the ALlog hybrid knowledge representation system where the Description Logics component is extended to the Web Ontology Language OWL DL. We implemented an OWL-log reasoner coupled to the OWL reasoner Pellet and explored different query-answering strategies. We conducted an experimental study using a modified version of the LUBM benchmark in orde...

The goal of this article is to map between Object Role Modeling (ORM) and Ontology Web Language 2 (OWL 2 DL). This mapping allows one to graphically develop his/her ontology using the ORM notation, while the ORM is automatically translated into OWL 2 DL. We map the most commonly used rules of ORM into OWL 2 DL which have the ability of decidability. DogmaModeler is extended to perform automatic...