Re: Comments on Last-Call Working Draft of RDF 1.1 Semantics

On Dec 9, 2013, at 9:12 PM, Pat Hayes <> wrote:

> On Dec 9, 2013, at 4:15 PM, Michael Schneider <> wrote:
>> There will be no further involvement into the discussion from my side, except for answering concrete requests, e.g. for clarification, etc. It's now up to the WG to make a decision. What I can say is that if this change makes it into PR,
>> I'm going to formally object, and my basic line of argumentation should be clear by now.
> It is not clear to me. As the change does not affect any entailments and does not alter the actual interpretation structures being described, and as the documents now (in reponse to your original comment) exactly define the 2004 notion of datatype map so as to provide backwards compatibility with earlier specifications which use the concept, I do not see what the basis is for your objection, other than that you prefer the older style of exposition. 

Let me slightly modify my stance here. Since writing this I have taken a careful look at the 2010 OWL 2 RDF specification you edited, and I see that you there make very detailed reference to much of the formal machinery defined in the 2004 RDF Semantics document, repeating and then modifying or extending many of the exact definitions, including those of datatype maps. In order to refer to the RDF 1.1 Semantics rather than the 2004 Semantics in the same way would require, I now see, extensive editorial changes to the 2010 OWL 2 RDF document, since many of those definitions have now been modified or in some cases removed from the RDF 1.1 Semantics altogether. However, the particular issue we are discussing here seems to be only one of these changes, and not one that affects any entailments in either RDF or OWL 2. It would be straighforward, if tedious, to re-word the relevant sections (chiefly 4.1 and 4.2, with minor wording changes in 3.3 and 3.4) so that they used the concepts of D-interpretation and recognized IRIs defined in the RDF 1.1 Semantics document, rather than referring to the datatype map construct used in the 2004 RDF specifications, while still describing exactly the same extended semantic structures related to RDF in the same way. (Other differences between the 2004 and 2013 RDF semantics descriptions seem to have more far-reaching editorial consequences; for example, that intepretations in RDF 1.1 are not defined with respect to a vocabulary. Others require changes to actual entailments, in particular the fact that ill-formed literals produce inconsistencies in RDF without using the RDFS extension.)

Nevertheless, in order to make the connection to the 2004 definitions more explicit, let me suggest that we change our wording by adding to the end of the first paragraph of section 7 so that it reads as follows:


Datatypes are identified by IRIs. Interpretations will vary according to which IRIs they recognize as denoting datatypes. We describe this using a parameter D on simple interpretations. where D is the set of recognized datatype IRIs. We assume that a recognized IRI identifies a unique datatype wherever it occurs, and the semantics requires that it refers to this identified datatype. The exact mechanism by which an IRI identifies a datatype IRI is considered to be external to the semantics, but we may describe this identification as a mapping from recognized IRIs to datatypes, called a <def>datatype map</def>. 

and then modify the change note as follows:

<Change note> In the 2004 Semantics specification, D was defined to be a datatype map rather than a set of IRIs.  This  permitted "non-standard" datatype maps which map IRIs to datatypes they do not identify (such as one that maps the IRI '' to the datatype identified by ). Semantic extensions based on such non-standard mappings are not sanctioned by this specification. 


I believe this establishes sufficient connection between the 2004 'datatype map' terminology and the 2013 'recognized IRI' terminology to enable conditions stated in the 2004 language to apply clearly to the 2013 specifications. Do you agree?


Received on Tuesday, 10 December 2013 08:22:53 UTC