Request for clarification on classes near `time:Instant` in OWL-Time

[ajnelson-nist]

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Is your feature request related to a problem? Please describe.
I noticed time:Instant appears in the gUFO class hierarchy, here:

gufo/gufo.ttl

Lines 1447 to 1451 in 6eb73ad

	### http://www.w3.org/2006/time#Instant
	time:Instant rdf:type owl:Class ;
	rdfs:subClassOf gufo:AbstractIndividual ;
	rdfs:comment "An gufo:AbstractIndividual that reifies time instants. It is used as a target of the gufo:hasBeginPoint and gufo:hasEndPoint object properties."@en ;
	rdfs:label "Instant"@en .

time:Instant is part of a class hierarchy with a parent and some siblings within its origin ontology OWL-Time: time:TemporalEntity is its parent, time:Interval a sibling at the same subclass depth as time:Instant, and time:ProperInterval a disjoint sibling of time:Instant, under time:Interval.

gUFO has time:Instant as a subclass of gufo:AbstractIndividual. Does this mean that time:Instant's nearby classes in the OWL-Time hierarchy are also gufo:AbstractIndividuals? E.g., is gufo:Event, as a concrete individual, automatically disjoint with time:Interval?

Describe the solution you'd like
It would be helpful to have some declared alignment with owl:Time, such as time:TemporalEntity going under gufo:AbstractClass; or, the alternative position being taken with an illustration of what under time:TemporalEntity is abstract vs. concrete; or, a stated non-commitment either way.

Describe alternatives you've considered
Alternatives are enumerated above. Either all, or some, of the time:TemporalEntity hierarchy is under gufo:AbstractIndividual.

Additional context
Knowing how gUFO treats the time:TemporalEntity hierarchy will help in understanding how the Allen relations as defined in owl:Time could relate gUFO objects.

[jpalmeida]

Hi Alex,

As a design principle, we wanted to say the least we could about OWL-Time and still allow gUFO users to reify time instants according to it.

Ideally, the whole time:TemporalEntity taxonomy would go under gufo:AbstractIndividual, as this is how we best interpreted the ontological nature of time instants and intervals in that specification.

However, there are two excerpts of the specification which are problematic (I've added emphasis in bold):

• The properties :hasTemporalDuration, :hasBeginning and :hasEnd, together with a fourth generic property :hasTime, support the association of temporal information with any temporal entity, such as an activity or event, or other entity.

and:

• The PROV-O classes prov:Activity and prov:InstantaneousEvent may be conceived as sub-classes of :TemporalEntity and :Instant respectively.

prov:Activity           rdfs:subClassOf    time:TemporalEntity .
prov:InstantaneousEvent rdfs:subClassOf    time:Instant .

We understand activities and events as concrete individuals. So, in the end, OWL-Time does not clarify the ontological nature of its temporal entities (instants included). This is unfortunate for that specification (and we'd hope it would be fixed simply by omitting these excerpts above).

Concerning Allen relations, they can be used for gufo:Events by constructing time:Intervals with the events' begin and end-points.

So, perhaps, we need to document this decision with a note in http://purl.org/nemo/doc/gufo

What do you say?

best regards,
João Paulo