Classical reasoning over ontologies has reached the point where it can deal with large real-world ontologies. This can largely be attributed to advances in research on description logics (DLs). A good example is the medical ontology SNOMED-CT, containing over 300,000 concepts and millions of binary relationships between them. SNOMED-CT can be represented as a DL ontology, and its subsumption hierarchy can be computed in a matter of minutes.

The obvious next step now is to extend reasoning over ontologies to cover non-classical cases, such as commonsense reasoning, a well established branch of AI. The first steps in that direction have been done by the ontology community, and while research along these lines has already resulted in initial tangible results, there is a need for a more coherent approach in order to speed up progress.

This need provides interesting challenges to both the ontology and commonsense reasoning communities. For the commonsense reasoning community it is a chance to determine to what extent techniques developed in its sub-areas, like non-monotonic reasoning (NMR), can be tailored to the requirements of the ontology community. For the ontology community it is an opportunity to determine whether existing results in this area can be sharpened and improved on by referring to results in the broader area of commonsense reasoning.

The topic of the workshop will hence be combining commonsense reasoning approaches and techniques with ontologies. One of the main motivations is to bring ideas from the well developed area of non-monotonic reasoning, e.g. reasoning about actions, argumentation and belief revision, for discussion in the realm of ontology engineering: evolution, debugging, update, merging, etc. Certainly these tasks can benefit from most of the advances in NMR and give new insights for research in that area as well.

Commonsense and Non-Monotonic Reasoning for Ontologies will be of interest to:

1. • Researchers in the ontology community, particularly DL researchers, interested in extending ontological reasoning to non-classical cases.
   

2. • Researchers in the knowledge representation and commonsense reasoning community interested in applying existing NMR techniques to the area of ontologies.
   

This workshop will focus on an emerging hot topic. As such, one of its immediate outcomes will be boosting a new and exciting hybrid research domain combining commonsense reasoning and knowledge engineering for ontologies.