Re: Clarification required: BP6 "use HTTP URIs for spatial things"

[snip]


> It is tricky - I've been confusing myself for the last couple of days at
> least! So if we _do_ conflate the real world thing (e.g. Eddystone
> Lighthouse) and the discerned feature (e.g. Eddystone Lighthouse seen as
> a vertical obstruction) then it would be acceptable to use <owl:sameAs>
> with no need for the "sameRealWorldEntityAs" property; e.g. ...
>
>     <http://example.com/sar/features/vo/EDY> owl:sameAs <
> http://example.org/maritime/navaid/2650253> .
>
> This would align with the common approach used in Linked Data where
> (authoritative) identifiers are reused across different domains, datasets
> and applications with the view to providing common "nodes" in the
> "knowledge graph". The BP doc actively encourages such reuse of identifiers
> (assuming that the data publisher / curator can be 100% sure that the
> identifier identifies the thing they're making statements about!). For
> example, we might want to encourage folks to reuse the identifier for
> Eddystone Lighthouse minted by Google for the Knowledge Graph: <
> https://g.co/kg/m/013qr8> (which I think is derived from an older
> Freebase identifier)
>
> If I've interpreted correctly (as above), then I will try to include a
> Note in the BP document alluding to feature discernment and the related
> cognitive process.
>
> Jeremy
>


We have to be very careful with recommending owl:sameAs for identifying
equivalence of resources (individuals). This page
<http://ontologydesignpatterns.org/wiki/Community:Overloading_OWL_sameAs>
(Overloading OWL sameAs) summarizes discussion about owl:sameAs in the
semweb community years ago and it specifically says that linking a thing
with data about that thing with owl:sameAs is abuse of owl:sameAs.

The paper When owl:sameAs isn't the Same: An Analysis of Identity in Linked
Data <https://www.w3.org/2009/12/rdf-ws/papers/ws21> goes further and says
that when two resources are linked by owl:sameAs they are expected to have
the same properties, and "[..] any statement that is given to a single URI
is true for every other URI that has an owl:sameAs link".

The reason that a satisfactory solution to asserting resource equivalence
did not seem available on the web was the reason the use case Modelling In
The Construction Sector
<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#ModellingInTheConstructionSector>
was
contributed, with its deriverd Subject equality requirement
<http://w3c.github.io/sdw/UseCases/SDWUseCasesAndRequirements.html#SubjectEquality>
.

Regards,
Frans