- From: Markus Lanthaler <markus.lanthaler@gmx.net>
- Date: Sun, 30 Mar 2014 19:51:11 +0200
- To: "'Pat Hayes'" <phayes@ihmc.us>
- Cc: <public-hydra@w3.org>, "'Peter F. Patel-Schneider'" <pfpschneider@gmail.com>, <public-lod@w3.org>, "'W3C Web Schemas Task Force'" <public-vocabs@w3.org>, "'Dan Brickley'" <danbri@danbri.org>
On Sunday, March 30, 2014 9:14 AM, Pat Hayes wrote: > On Mar 29, 2014, at 8:10 PM, Peter F. Patel-Schneider wrote: > > On 03/29/2014 03:30 PM, Markus Lanthaler wrote: > >> Schema.org doesn't suffer from this issue as much as other vocabularies > >> do as it isn't defined with RDFS but uses its own, looser description > >> mechanisms such as schema:domainIncludes and schema:rangeIncludes. > >> So what I'm really looking for is a solution that would work in general, > >> not just for some vocabularies. > > > > I would like to see some firm definition of just how these looser > > description mechanisms actually work. > > Yes, I agree. Let me put the question rather more sharply. What follows > from knowing that > > ppp schema:domainIncludes ccc . ? > > Suppose you know this and you also know that > > x ppp y . > > Can you infer x rdf:type ccc? I presume not, since the domain might > include other stuff outside ccc. Right > So, what *can* be inferred about the > relationship between x and ccc ? As far as I can see, nothing can be > inferred. If I am wrong, please enlighten me. But if I am right, what > possible utility is there in even making a schema:domainIncludes > assertion? It is a hint as to what might be at the other end. It sets an expectation for consumers of such data. Similar to how a labeled link on an HTML page sets an expectation of what you'll find when you follow it. It is not a contract because in a lot of cases you don't control the target of that link. RDFS is kind of a contract as it "infects" the target.. even if you don't control it. It is up to the consumer to trust such assertions or not. > If "inference" is too strong, let me weaken my question: what possible > utility **in any way whatsoever** is provided by knowing that > schema:domainIncludes holds between ppp and ccc? What software can do > what with this, that it could not do as well without this? Software can't do too much with unless you start talking about probabilistics.. the likelyhood to find a schema:Person at the end of a schema:author link is higher than finding a schema:Event for instance. Other than that, it can be used to generate documetation as the one shown on schema.org. > Having a piece of formalism which claims to be a 'weak' assertion > becomes simply ludicrous when it is so weak that it carries no content > at all. This bears the same relation to axiom writing that miming does > to wrestling. It clearly provides value IMO. The value, however, is indeed mostly for humans and not for machines. As are labels, descriptions etc. I don't really see a problem with this. -- Markus Lanthaler @markuslanthaler
Received on Sunday, 30 March 2014 17:52:00 UTC