Re: Singularity: why has "children" not been renamed to "child"?

On 5/9/2013 10:02, Dan Brickley wrote:
> One of the trickier aspects of describing property semantics with OWL 
> is that we keep adding new terms into the evolving vocabulary. I am 
> wary of making strong claims in machine form today which would be 
> countered if, for example, we added a second or third type for some 
> property which currently only has one or two expected (ranges, or 
> domains) types listed.

Yes I agree and understand that. But owl:inverseOf is hopefully a case 
that can still be stated strongly as it's unlikely that the same 
property will have different inverses in the future. Likewise, I hope 
the cardinality information is the same for all instances 
(owl:FunctionalProperty) or could otherwise be captured locally in the 
context of a class (mapping to owl:Restriction).

--- Thinking out loud now:

Regarding the rdfs:domains, in my personal opinion there are some 
reasons in favor of simply avoiding this scenario: just do not encourage 
property reuse, i.e. multiple domain classes for the same property.

Take "location" as an example. It's currently allowed for Event and 
Organization. Apart from readability, I do not see reasons why the same 
property was reused here. It could just as well have been 
"eventLocation" and "headquarterLocation", possibly with an 
rdfs:subPropertyOf "location". Or introduce a shared superclass such as 
ThingWithLocation (not sure if multiple inheritance is supported here) 
and attach "location" to that.

I know these things would be hard to change now, but maybe food for 
thought in the future evolution. Especially if you simply add new 
domains to a property such as "location" in the future, then existing 
applications may break because they have made certain assumptions about 
the old property. From an RDF point of view, I'd rather like to be able 
to efficiently query for schema:eventLocation than schema:location 
without also having to check the rdf:type of that thing.

I am aware that there are arguments in favor of reusing properties, so 
please regard this only as one opinion among others.

Cheers,
Holger

Received on Thursday, 9 May 2013 00:26:02 UTC