[sdw] TIME: Suggestions for alignment with PROV-CONSTRAINTS "precedes"? (#1430)

ajnelson-nist has just created a new issue for https://github.com/w3c/sdw:

== TIME: Suggestions for alignment with PROV-CONSTRAINTS "precedes"? ==
This is an Issue about how to interpret a certain property in OWL-Time, [`time:before`](https://www.w3.org/TR/owl-time/#time:before).  There is a detour through PROV that explains why I'm asking. It is possible this issue also shows a point of needed clarification in the current OWL-Time draft.

While reviewing the non-normative alignment of TIME and PROV here ...


... I saw that there is an alignment axiom for `prov:Activity`:

  rdfs:subClassOf time:TemporalEntity ;

From working with PROV, I had come to think it would be more appropriate for `prov:Activity` to be a subclass of `time:ProperInterval`.  However, when double-checking my sources, I wasn't able to find a strict requirement that, given a `prov:Activity` with a `prov:Start` and `prov:End`, that `prov:Start` was required to happen strictly before `prov:End`.

From review of PROV-CONSTRAINTS, I came across this evidence that a `prov:Activity` is permitted to be instantaneous:

* [Constraint 30 (start-precedes-end)](https://www.w3.org/TR/prov-constraints/#start-precedes-end) uses the defined term "precedes".
* ["precedes"](https://www.w3.org/TR/prov-constraints/#dfn-precedes) is defined like so: "Specifically, precedes is a preorder between instantaneous events. A constraint of the form e1 precedes e2 means that e1 happened at the same time as or before e2."  So, "precedes" is roughly writable as "<=".
* "strictly precedes", in the same paragraph as "precedes", is defined to have the two related (instantaneous) events not occur at the same time.
   - The only usage of "strictly precedes" that I could see in PROV-CONSTRAINTS was [Constraint 42 (derivation-generation-generation-ordering)](https://www.w3.org/TR/prov-constraints/#derivation-generation-generation-ordering).
* Reviewing "Activity" [in PROV-O](https://www.w3.org/TR/prov-o/#Activity) and [in PROV-DM](https://www.w3.org/TR/2013/REC-prov-dm-20130430/Overview.html#term-Activity) didn't provide a hint on required inequality of its start or ends.
* Reviewing "Start" [in PROV-O](https://www.w3.org/TR/prov-o/#Start) and [in PROV-DM](https://www.w3.org/TR/2013/REC-prov-dm-20130430/Overview.html#term-Start) shows a reliance on "follows" (inverse of "precedes") that is not clarified as being a strict "<" or permissive "<=" binary relationship.

Where all this circles back to OWL-Time: I see two properties that can be used to relate one `time:Instant` to another `time:Instant`, [`time:before`](https://www.w3.org/TR/owl-time/#time:before) and [`time:after`](https://www.w3.org/TR/owl-time/#time:after).  The definitions, as currently worded, do not make explicit whether the properties permit equality of the instants being related.  Personally, my normal reading of the words "before" and "after" imply a strict-inequality relationship; but, apparently W3C editorial policy in the past has permitted a standard to be posted where "precedes" could be defined as "<=", so now I feel the need to check.

If I have a statement `x time:before y .`, can `x` and `y` refer to the same `time:Instant`?

For the sake of finding a way to align with the "precedes" definition in PROV-CONSTRAINTS: Is there a predicate in OWL-Time that defines "<=" between `time:Instant`s?

Should one of `time:before` or `time:after` be designated an `owl: AsymmetricProperty`?  An `owl:ReflexiveProperty` or `owl:IrreflexiveProperty`?  `time:before` is currently a `owl:TransitiveProperty`, so it seems some thought was put into property specializations, but I'm not sure where notes on those specializations might be.

Please view or discuss this issue at https://github.com/w3c/sdw/issues/1430 using your GitHub account

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Received on Monday, 26 June 2023 21:38:43 UTC