disjoint_from is a tag in oboformat1.2.
If X disjoint_from Y, then it means that nothing can be both an instance of X and an instance of Y at the same time. It also follows that nothing can be an is_a descendant of both X and Y.
- It does not mean that X and Y are spatially non-overlapping.
- It does not mean that there are no gene products annotated to both X and Y
The tag has the same meaning as disjointWith in OWL. See OWL spec
oboformat1.3 may allow the declaration of disjoint sets. This will make it easier for cases where a class has multiple is_a children, all mutually disjoint; it can get tedious recording every pairwise disjointness link
BP granular levels
cellular, multicellular organismal and multi-organism processes are declared mutually disjoint
The top 3 nodes in each ontology (BP, MF, CC) can be declared mutually disjoint (remember, this does not in itself prohibit part_of or other kinds of links between the 3 ontologies).
This could be implemented easily. Although we have no cross-ontology links prior to Oct 2008, this should not be a hindrance any more than consider/replaced_by links that span the 3 ontologies
Initial results suggest that adding disjointness constraints to some top-level CC pairs may be useful for detecting TPVs.