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RE: [RDF-CONCEPTS] Skolemization

From: Markus Lanthaler <markus.lanthaler@gmx.net>
Date: Tue, 11 Jun 2013 21:23:37 +0200
To: "'public-rdf-comments'" <public-rdf-comments@w3.org>
Message-ID: <00f001ce66d9$2e06ff70$8a14fe50$@lanthaler@gmx.net>
On Tuesday, June 11, 2013 7:19 PM, David Booth wrote:
> Specific wording changes that I suggest:
> 
> 1. Change:
> 
>      "Systems wishing to do this SHOULD mint a new, globally
>      unique IRI (a Skolem IRI) for each blank node so replaced."
> 
> to:
> 
>      "Systems choosing to do this MUST mint a new, globally
>      unique IRI (a Skolem IRI) for each blank node so replaced.
>      Each such Skolem IRI SHOULD conform to the syntactic
>      requirement for a well-known IRI [WELL-KNOWN] with the
>      registered name genid. This is an IRI that uses the HTTP or
>      HTTPS scheme, or another scheme that has been specified to
>      use well-known IRIs; and whose path component starts with
>      /.well-known/genid/."
> 
> 2. Delete the paragraph:
> [[
> Systems that want Skolem IRIs to be recognizable outside of the system
> boundaries should use a well-known IRI [WELL-KNOWN] with the registered
> name genid. This is an IRI that uses the HTTP or HTTPS scheme, or
> another scheme that has been specified to use well-known IRIs; and
> whose
> path component starts with /.well-known/genid/.
> ]]

Since we are already discussing this, and considering your two proposals
regarding the JSON-LD spec, I wonder how Skolem IRIs fit into a (RDF-based)
Linked Data system. Certainly (admitted not always but most of the time)
they wouldn't resolve to anything useful. Most likely they would even result
in 404s - and yet it is recommended to use HTTP URLs.

What about systems which are not capable of minting "new, globally unique
IRI[s]"? What does that statement actually apply to? RDF Concepts doesn't
define any product classes, in fact it states:

    Implementations cannot directly conform to RDF 1.1
    Concepts and Abstract Syntax, but can conform to such
    other specifications that normatively reference terms
    defined here.

In the same section, RDF Concepts currently also says

    This transformation does not appreciably change the meaning
    of an RDF graph, provided that the Skolem IRIs do not occur
    anywhere else. It does however permit the possibility of
    other graphs subsequently using the Skolem IRIs, which is
    not possible for blank nodes.

I think the last statement is not entirely correct. It is possible in
datasets.


Cheers,
Markus


--
Markus Lanthaler
@markuslanthaler
Received on Tuesday, 11 June 2013 19:24:09 UTC

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