Re: D-entailment question in http://www.w3.org/TR/2014/PR-rdf11-mt-20140109/

Hi Richard,

(not meant to open a new comment, but just to re-explain my original comment)

On 28 Jan 2014, at 09:35, Richard Cyganiak <richard@cyganiak.de> wrote:

> Axel,
> 
> (Not an official WG response)
> 
> The definitions you're looking for are in RDF 1.1 Concepts.

understood, I am fine with the definitions in that document, but let me re-explain why I was confused:

>> a) to add more explanatory text or pointers to other specs to make these definitions more self-contained.


I meant to say it would be nice if there were some more links to the CONCEPTS document or within the MT document to definitions (editorial), e.g.
   the word “datatype” in the old RDF-mt spec is directly linked to the definition 
   http://www.w3.org/TR/rdf-mt/#defDatatype (which was within the document itself, not a part of the Conepts document, which may have confused me) … if you move the definition to the Concepts doc, that’s ok, but at the moment the choice between explicit references to the concept document at some places, e.g. "RDF literals and datatypes are fully described in Section 5 of [RDF11-CONCEPTS]” and linking directly whenever you use a concept defined herein or in the concepts document (such as “datatype”, defined in CONCEPTS, “L2V” defined herein, but also somewhat in CONCEPTS, though less formally) seems a bit arbitrary at the moment and it would be nice if this was a bit more consistent.

>> b) explain, even if only in an informal section, how custom datatypes should be defined (which several existing RDF datasets do)

Particularly, I am not too happy with the definition of the verb “identify” http://www.w3.org/TR/2014/PR-rdf11-mt-20140109/#dfn-identify
which, frankly is more confusing than enlightning to me… 

"IRI meanings may also be determined by other constraints external to the RDF semantics; when we wish to refer to such an externally defined naming relationship, we will use the word identify and its cognates.”

in a way, it seems that this wants to tell me that IRIs i may be interpreted as different things (as a resource and as a datatype), 
where the term “identify” seems to be used to implicitly define the (fixed?) interpretaiton function for 
a datatype, let’s call it I_datatype() but the spec gives only a formal account for I_resource(i), but not 
for I_datatype(i), whereas it DOES seem to say that 
   I_resource(i) =  I_resource(j) implies that I_datatype(i) =  I_datatype(j)

I find the mix of informal and formal definitions here a bit hard to grasp, coming from the IMO fairly clean definition of datatype maps in the old RDF spec. 

HTH to make my comment mor concrete,
Axel


> A good understanding of Concepts is sort of a prerequisite for any of the other specs.
> 
> Best,
> Richard
> 
> 
>> On 28 Jan 2014, at 07:53, Axel Polleres <axel.polleres@wu.ac.at> wrote:
>> 
>> Dear RDF 1.1 WG,
>> 
>> First of all let me thank the WG for their efforts and work on gettin the new RDF1.1 spec to PR.
>> My new affilation organization (WU Wien) has recently joined W3C and I have started looking 
>> in a bit more detail into the new specs.
>> 
>> When looking over the definition of D-entailment, and also related comments on the list, I have some small question:
>> 
>> If I see it correctly, and that’s good news, D-entailment is no longer stacked on top of RDFS Entailment. I very much welcome this change.
>> Next, I wonder only about one thing regarding the removal of datatype maps. As I understand the discussions, the intention here is 
>> to simplify things, by assuming that known IRIs *identify* datatypes, i.e. there is a fixed interpretation for such known IRIs, 
>> and that this fixed interpretation of a datatype IRI aaa is associated with a known lexical-to-value mapping L2V.
>> 
>> However, Section 7.1 seems to have no pointers to a *definition* of what is a *datatype* or a *lexical-to-value* actually is, nor give any information of how a custom datatype is defined, e.g. 
>> 
>> "For every other IRI aaa in D, I(aaa) is the datatype identified by aaa, and for every literal "sss"^^aaa, IL("sss"^^aaa) = L2V(I(aaa))(sss)”
>> 
>> seems to miss that L2V is the associated lexical-to-value mapping for I(aaa).
>> 
>> Also, I find the remote definition of *identify* in section 4 ("when we wish to refer to such an externally defined naming relationship, we will use the word identify and its cognates.”)
>> insufficient to give a proper definition to what a datatype is.
>> 
>> I would kindly ask the group for two things:
>> a) to add more explanatory text or pointers to other specs to make these definitions more self-contained.
>> b) explain, even if only in an informal section, how custom datatypes should be defined (which several existing RDF datasets do)
>> 
>> If I understand this correctly, such informal addition as well as adding explaining text or references to other specs containing the resp. definitions 
>> would not be a substantial change, and not affect PR status.
>> 
>> best regards,
>> Axel
>> 
>> 
>> 
>> --
>> Prof. Dr. Axel Polleres
>> Institute for Information Business, WU Vienna
>> url: http://www.polleres.net/  twitter: @AxelPolleres
>> 
>>

Received on Thursday, 30 January 2014 17:39:18 UTC