part_of must be declared transitive

[cmungall]

BTO uses the RO relation http://purl.obolibrary.org/obo/BFO_0000050 (part of) to connect body parts as is standard for many OBO ontologies.

However, BTO doesn't declare this relation to be transitive. This is to be excused, the OBO documentation could be improved in how it talks about how relations should be imported.

While this doesn't affect some applications such as browsing in OLS, for an increasing number of applications that rely on OWL reasoning, it means that queries with BTO will frequently incomplete (sometimes in ways that are quite detrimental but not easily noticed at the time).

For example, any application that uses relation graph will get incomplete answers when doing the transitive closure over is-a and part-of from the root node BTO:0000000. E.g. it won't include "endocuticle" because this involves two hops:

This is easily fixed by adding a transitivity declaration. If your source is obo format, add transitive: true. If OWL, check the box here

Thank you!