RE: OWL-Time - ISSUE-65: General purpose temporal predicates

The class :TemporalEntity is already in the ontology. It has subclasses :Instant and :Interval. Which looks comparable to Geometry as superclass of Point, Line, Polygon etc at first glance at least. Which would make it _not_ a feature. Which is why I raised the issue.

Simon

________________________________
From: Krzysztof Janowicz <janowicz@ucsb.edu>
Sent: Wednesday, 28 December 2016 9:08:33 PM
To: Joshua Lieberman; Cox, Simon (L&W, Clayton)
Cc: public-sdw-wg@w3.org
Subject: Re: OWL-Time - ISSUE-65: General purpose temporal predicates

I like Josh's argumentation and agree on the separation of a temporal entity from the time model the same way we deal with spatial entities and geometries. This would also enable us to easily support multiple temporal granularities the same way we can have multiple geometries per feature.


On 12/28/2016 01:03 PM, Joshua Lieberman wrote:
Doesn't that depend on what a Temporal Entity "is". The ISO - OGC feature-geometry disjunction is based on Geometry being a model property for a Feature (Spatial Thing), not the Feature itself. It seems to me that this could have a parallel in OWL-Time, with Temporal Entity being the thing with an extent in time, and Duration or TimePosition being a model property for that Entity. If that parallel is valid, then it wouldn't be inconsistent to say that a Feature is-also-a Temporal Entity if it has a Duration or TimePosition model property.

Josh

On Dec 28, 2016, at 8:16 PM, <mailto:simon.cox@csiro.au> simon.cox@csiro.au<mailto:simon.cox@csiro.au> wrote:

The primary goal of OWL-Time is to implement Allen's temporal relations in OWL, so all the OWL-Time predicates have Temporal classes as both domain and range. For example, 'hasBeginning' relates a temporal entity to a temporal instant. This means that attaching timing information to any event or activity using one of these predicates implies that it _is_ a "Temporal Entity". This would be inconsistent with the approach used in the OGC/ISO Feature Model for associating geometry with a feature, in which feature types are _nt_ subclassed from geometries, but have associations with geometries. At least that would be the argument if time is treated the same as geometry.

As there appears to be interest in standard predicates to associate timing information to events or activities, we have a problem. One solution (ISSUE-64) would be to relax the global domain constraints on the existing predicates. Alternatively, we can create some general purpose object properties, such as the following:

:activityBeginning
  rdfs:comment "Beginning of an event or activity."@en ;
  rdfs:range :Instant ;
.
:activityDuration
  rdfs:comment "Duration of an event or activity, expressed as a scaled value"@en ;
  rdfs:range :Duration ;
.
:activityDurationDescription
  rdfs:comment "Duration of an event or activity, expressed using a structured description"@en ;
  rdfs:range :GeneralDurationDescription ;
.
:activityEnd
  rdfs:comment "End of an event or activity."@en ;
  rdfs:range :Instant ;
.
:activityTime
  rdfs:comment "Supports the assignment of a temporal entity (instant or interval) with an event or activity"@en ;
 rdfs:range :TemporalEntity ;
.

The slightly awkward names are because hasBeginning, hasDuration etc are already in use.
Not at all wedded to activity*. Could be event* or something else if anyone has any smart ideas.

I've added these to the branch here:
<https://github.com/w3c/sdw/blob/simon-time-predicates/time/rdf/time.ttl>https://github.com/w3c/sdw/blob/simon-time-predicates/time/rdf/time.ttl

OTOH, some upper-level ontologies make a fundamental distinction between time-bounded entities (occurrent or perdurant) and non-time-bounded entities (continuant or endurant). If we accept this viewpoint, then we might just use the original OWL-Time predicates and accept the entailment.  I guess it depends which fundamental commitment we are willing to make.

Simon

Simon J D Cox
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Environmental Informatics
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