Pushing the limits of OWL, rules and protege a simple example

The Semantic Web brings powerful languages for creating models, based on Description Logics and Rules. These languages are used within ontology engineering tools and applied in strong and efficient reasoners. Working within the context of a Summer School, we explored these technologies by creating a small and easy to understand example, working firstly with OWL alone, and introducing SWRL rules as needed, to automatically classify a number of instances according to some intuitively simple criteria. We present the example OWL ontology, SWRL rules, and the issues and problems we encountered. Our experience highlights the capabilities and limitations of OWL and of SWRL, not in theoretical but in practical terms, and points to the need for better tool support, but is primarily a lesson in "traps for young players" in terms of formulating classifications, that we hope will be instructive for Semantic Web students following in our footsteps, and their tutors.