W3C home > Mailing lists > Public > public-rif-wg@w3.org > December 2007

Re: Another try at subclass

From: Axel Polleres <axel.polleres@deri.org>
Date: Wed, 19 Dec 2007 11:41:22 +0000
Message-ID: <47690362.6080309@deri.org>
To: Chris Welty <cawelty@gmail.com>
CC: "Public-Rif-Wg (E-mail)" <public-rif-wg@w3.org>

Chris Welty wrote:
> 
> 
> 
> [Hoping to grab those last few free cycles before people go away for the 
> next two weeks]
> 
> </chair>
> At this point I have heard no objection to this proposal, so I will try 
> to make it a little more precise and add the rif:type relation as well. 
> Basically, Jos and Dave, I am hoping to hear from you by email that you 
> would not object (I you can live with) the following amendment, which 
> would live (I believe) in the RDF compatibility document:
> 
> rif:subClassOf rdfs:subproperty rdfs:subClassOf .
> 
> This plus the transitivity semantics given to by Michael already in BLD, 
> should  addresses the concern regarding the relationship to 
> rdfs:subClassOf.
> 
> Finally, I suggest that either:
> rif:type owl:sameAs rdf:type
> or we just use rdf:type

+1 for the latter

> Note that this still requires the semantics to say:
> 
> For all elements eo, ec, es ∈ D, the following must hold:
> mint(Iisa(eo, ec), Isub(ec,es))   ≤t   Iisa(eo, es)
> 
> (which is already in the semantics for #)
> 
> The other objection to having Rif:type and rif:subclassof is why do we 
> even need it.  The answer there is that many people (in the WG) seem to 
> want it and it definitely helps address our coverage requirement since 
> they are part of *so many* rule languages.

I think I buy into the argument now that this is simply the 
non-reflexive version of rdf:subclassOf finally. Fair enough for me that 
way and might be useful. With rdf:type instead of rif:type this 
perfectly makes sense to me.

Axel

> I realize that this is not enough for agreement, but I hope it is enough 
> to remove objections.
> 
> <chair>
> 
> -Chris
> 
> 
> Dave Reynolds wrote:
>> Chris Welty wrote:
>>>
>>>
>>> </chair>
>>>
>>> Back in August I proposed a "friendly amendment" for the 
>>> rif:subClassOf relation (aka ##) saying that:
>>>
>>> rif:subClassOf rdfs:subproperty rdfs:subClassOf .
>>>
>>> Michael was not opposed, he thought that it was obvious.  Jos replied 
>>> as below, indicating some possible softness on the point.  I don't 
>>> think DaveR responded. But I didn't push on it as some other thing 
>>> must have come up (like vacation probably), and the thread ended with 
>>> Jos' message below.
>>
>> I think we discussed it briefly at a telecon.
>>
>>> So before we give up on it, because I do think it would be useful to 
>>> have in BLD, I'd like to see if this will make a difference to 
>>> anyone, specifically the objectors to having rif:subClassOf (DaveR, 
>>> Jos, ?).
>>
>> I do think it helps a little.
>>
>> It doesn't answer the question of why we are creating this 
>> semi-parallel set of concepts in the first place.
>>
>> However, it does address one of the sub-issues viz it helps us answer 
>> the obvious question "so how do rif:type and rif:subClassOf related to 
>> the similar sounding RDFS/OWL properties?". At a minimum if we put 
>> these in BLD we need a clear answer to that question and this does 
>> that. Well does half of it - would need a similar thing for rif:type 
>> (or whatever the URI for # is).
>>
>> Dave
> 


-- 
Dr. Axel Polleres
email: axel@polleres.net  url: http://www.polleres.net/

rdf:Resource owl:differentFrom xsd:anyURI .
Received on Wednesday, 19 December 2007 11:41:47 GMT

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