region, area, headache

A constant and ongoing debate during our Tuesday HAO group discussion is the nature of regions and areas. In the classic approach areas have well defined boundaries, whereas regions have some boundary or compartmentalization that is not well defined. For example a region might be defined in part by a change of color wherein the precise point at which the color changes is not well defined. An example of an area might be the interocellar area, which is bound by three lines that join the centers of the ocelli. One is very precise, the other is not.

In the context of an ontology you can think of the two as matter and anti-matter. An ontology necessarily defines classes in a very specific way. Region, as we have discussed it, is a thing that has at least some non-defined boundary (areas have well defined material boundaries). Therefor regions are undefined, and may not belong in the ontology.

Our temporary solution is to assume that if something is a region in the "no boundaries/can't define a boundary" sense it doesn't belong in the ontology. We've moved everything previously under region to area, and have begun to rework some classical terms in such a way that they can be explicitly defined. For example look at the new definition for gena, a term which has never (to our knowledge) been adequately defined.

Note that areas can be defined by immaterial anatomical entities (e.g. lines connecting ocelli or planes  tangential to some reference line).

Note that this is largely a pragmatic resolution that lets us get on with other things. If you have any feedback or experience in this regard we'd love to hear it.