Fig. 5

Two alternative models for documenting absences using the instance-based ABox semantic graph approach. Within the Phenotype Knowledge Graph approach, the observation “insect abdomen lacks an ovipositor” can be modeled in two alternative ways. Top: Shows a representation of the observation using only ABox expressions. This requires the introduction of the object property has not part any that has an instance as a domain restriction and a class as range restriction. This is not part of the OWL syntax and would require the introduction of additional tools for making it machine-actionable. Bottom: Shows a representation of the observation using a combination of ABox and TBox expressions. The instance of insect abdomen instantiates not only the class insect abdomen but also the class absent ovipositor phenotype, which is characterized as the complement class of the class of entities that have some ovipositor as their part. This description is compliant with description logics and is directly machine-actionable. Purple-bordered box = instance resource; yellow-bordered box with rounded corners = ontology class resource; grey-bordered box with rounded corners = anonymous class; blue-bordered octagon = object property class; labeled arrow = property resource