Ants caught in the semantic Web: a study in the application of description logic to animal systematics

Scientists have been organising the forms of natural life into structured hierarchical systems since Linnaeus in the 18th century. Much more recently, computer scientists have developed a class of languages, called description logics (DL), that are aimed at describing concepts so that they may be automatically classified in hierarchical structures. These languages are being adopted in recent proposals for ontology definition that underly the semantic Web, particularly OWL-DL (Bechofer et al., 2003). In this paper we study the applicability of modern description logics to the application of animal systematics. We would like to improve both the process of scientific classification itself, and the methods for communication and integration of taxonomic knowledge. As a case study, we consider a published scientific treatment of Epopostruma, a genus of Australian Formicidae (ants) (Shattuck, 2000). We focus on expressing the morphological characters of Epopostruma, that is the features that derive from the form, structures, homologies and metamorphoses which characterise an individual. We express these characters in the description logic ALCQHIO_R⁺(D)^- underlying OWL-DL. Racer (Haarslev and Moller, 2001) is a readily-available reasoner ALCQHIO_R⁺(D)^-, and is used in this paper to support the development of the DL application to animal systematics. We have used the native syntax of Racer for DL expressions in this paper. We find that most of the language used in a scientific description is readily adapted to the formal description logic language, with the exception of spatio-temporal elements and some higher-order constructs. We show that the reasoning capability is sufficient for consistency checking and retrieval of taxonomic knowledge. We discuss some benefits of the representation to assist the work of biological systematists.