Untangling Taxonomies and Relationships:

The GALEN prALogramme has been developing medical ontologies collaboratively for nearly a decade. The ontologies are large and formulated in a specialised description logic, GRAIL. The programme is a broad collaboration of over a dozen groups, most with no prior experience of developing formal ontologies. The programme has developed a methodology for loosely coupled development using layers of intermediate representations, guidelines and tools which minimises training requirements for domain experts and effort by central knowledge engineers. Issues arise both from problems in formal representations and from the idiosyncrasies of the medical domain. Issues dealt with include ‘tangled’ taxonomies, part-whole and locative relationships, defaults and exceptions, semantic normalisation, and the difference between medical convention and strict logical criteria for correctness.