A methodology for in situ migration of a hand-crafted DAG (Directed Acyclic Graph) to an explicitly described, structurally validated OWL version is presented. The original DAG is a dynamic entity, being updated daily. Well known untangling methodologies recommend wholesale re-coding in one big hit. Unable to do this, we tackle portions of the DAG, dissecting lexical phrases used as terms to property based descriptions in OWL. Some portions of the Gene Ontology are amenable to this, others need more human input. OWL offers benefits at all stages. The different levels of expressivity are presented in a model called “feature escalator”, where the user can choose the expressivity needed in each level. The results of applying the methodology to some areas of the Gene Ontology demonstrate the validity of the methodology to migrate DAGs to more expressive and formal languages like OWL.

We would like to thank Michael Ashburner, Amelia Ireland, Jane Lomax and Chris Mungall, of the GO consortium, without whose help this work would not have been possible. We would also like to thank Olivier Dameron for technical help. Chris Wroe was supported by the GONG project grant (DARPA DAML subcontract PY-1149 from Stanford University) and the myGrid eScience pilot project grant (EPSRC GR/R67743).