On 12 June 2011 16:26, Richard Cyganiak <rich...@cyganiak.de> wrote: > Hi Pat, > > On 12 Jun 2011, at 00:33, Pat Hayes wrote: >>>> Nothing is gained from the range assertions. They should be dropped. >>> >>> They capture a part of the schema.org documentation: the “expected type” of >>> each property. That part of the documentation would be lost. Conversely, >>> nothing is gained by dropping them. >> >> Let me respectfully disagree. Range assertions (in RDFS or OWL) do *not* >> capture the notion of "expected type". They state a strict actual type, and >> cannot be consistently be "over-ridden" by some other information. Which has >> the consequence that these are liable to be, quite often, plain flat wrong. >> Which in turn has the consequence that there is something to be gained by >> dropping them, to wit, internal consistency. They are not mere >> documentation; they have strictly entailed consequences which many actual >> reasoners can and will generate, and which to deny would be to violate the >> RDFS specs. If you don't want these conclusions to be generated, don't make >> the assertions that would sanction them. > > Data on the Web is messy. You cannot reason over it without filtering it > first. I think it is useful to document how data publishers are *expected* to > use these terms, even if we know that many will -- for good or bad reasons -- > use them in *unexpected* ways. > >> For documentation, use the structures provided in RDFS for documentation, >> such as rdfs:comment. > > rdfs:comment is for prose. We explicitly know the “expected types” of > properties, and I'd like to keep that information in a structured form rather > than burying it in prose. As far as I can see, rdfs:range is the closest > available term in W3C's data modeling toolkit, and it *is* correct as long as > data publishers use the terms with the “expected type.”
I don't think it is that close to "expected type", or at least it's kinda back to front. If we have - :Colour a rdfs:Class . :hasColour a rdf:Property . :hasColour rdfs:range :Colour . - and someone makes a statement <#something> :hasColour <#wet> . then we get <#wet> a :Colour . no? so it's not an expectation thing, it's an inference that comes after the fact...if you see what I mean. As Pat suggested, I think this could easily lead to unintended conclusions. Cheers, Danny. -- http://danny.ayers.name
