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Re: Proposal for ISSUE-40 Skolemization

From: Ivan Herman <ivan@w3.org>
Date: Thu, 12 May 2011 16:14:47 +0200
Cc: "RDF-WG public-rdf-wg@w3.org" <public-rdf-wg@w3.org>
Message-Id: <AE47D818-9149-48AC-B3D5-764587920B6C@w3.org>
To: Richard Cyganiak <richard@cyganiak.de>

On May 12, 2011, at 15:36 , Richard Cyganiak wrote:

> On 12 May 2011, at 13:12, Ivan Herman wrote:
>> Just to clarify: in the course of the discussion we mentioned the alternative of shorter and friendlier, albeit non dereferencable URIs (not replacing the .well-known but as another possibility); I think one idea was to use urn:steveH:XXXXX. Is the intention that we do not go down that line? Just checking...
> 
> Several options were discussed:
> 
> - steveH:xxx
> - urn:steveH:xxx
> - urn:uuid:xxx
> - tag:w3.org,2011:steveH:xxx
> - tag:yourdomain:/.well-known/steveH/xxx
> - http://yourdomain/.well-knonwn/steveH/xxx
> 
> Of these, I had the impression that there is the most solid case for the last one, so that's what I put in the proposal.
> 
> Of course it could mention more than one option, but the fewer the better.
> 

I will not fight for this, because I am also happy to keep to one, but, if this is the last round of discussion (you see how optimistic I am?:-), it is worth making the choices clear.

Ivan


> I'd be tempted to put the proposal to the vote with only the HTTP option and see if it draws any objections.
> 
> Best,
> Richard
> 
> 
> 
>> 
>> Ivan
>> 
>> P.S. I actually think steveH is a perfect keyword:-)
>> 
>> 
>> 
>> On May 12, 2011, at 13:47 , Richard Cyganiak wrote:
>> 
>>> Below is a complete proposal including intro text and detailed wording about the .well-known mechanism, based on a combination of the original proposal from the wiki, and PatH's comments. It's also on the wiki here:
>>> http://www.w3.org/2011/rdf-wg/wiki/Skolemisation#Updated_Proposal
>>> 
>>> 
>>> On 28 Apr 2011, at 06:10, Pat Hayes wrote:
>>>> I would prefer to avoid the "skolem" terminology altogether.
>>> 
>>> I am fine with avoiding “skolem”. But I believe that *some* term is necessary. First, writing the spec is awkward if one has to repeatedly refer to “an IRI that has been introduced solely to replace a blank node”. Second, I believe that eventually we and others will come to use *some* shorthand term in everyday technical conversation, so why not just bite the bullet and define a term for it in the spec.
>>> 
>>> I'll stick to “Skolem IRI” for now, until another term has been proposed. I removed mentions of “Skolemization”.
>>> 
>>>> it really ought to be capitalized, as it is a direct use of the name of Theo Skolem.
>>> 
>>> Thoralf. I have now capitalized the term.
>>> 
>>>> It is not clear what is meant by " identifiable by other systems". Identifiable as being skolem URIs? Or in some stronger sense of 'identifiable'? If the former, I suggest the wording "identifiable by other systems as Skolem URIs"
>>> 
>>> This wording seems fine. I ended up using “recognizable outside of the system boundaries” to avoid “identify” and talking about “systems and other systems”.
>>> 
>>> The complete proposal is below.
>>> 
>>> Best,
>>> Richard
>>> 
>>> 
>>> PROPOSAL FOR ADDRESSING ISSUE-40
>>> 
>>> Add the following in RDF Concepts, Section 6.6 Blank Nodes
>>> http://www.w3.org/TR/rdf-concepts/#section-blank-nodes
>>> 
>>> 
>>> 6.6.1 Replacing blank nodes with IRIs
>>> 
>>> Blank nodes do not have an intrinsic name in the RDF abstract syntax. In situations where such a name is required, implementations MAY systematically replace blank nodes in an RDF graph with IRIs. Systems wishing to do this SHOULD mint a new, globally unique IRI for each blank node. Such IRIs are known as ''Skolem IRIs''.
>>> 
>>> Systems may wish to mint Skolem IRIs in such a way that they can recognize the IRIs as having been introduced solely to replace a blank node, and map back to the source blank node where possible.
>>> 
>>> Systems which want Skolem IRIs to be recognizable outside of the system boundaries SHOULD use a well-known IRI [RFC5785] with the registered name “SteveH”. 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/SteveH/ .
>>> 
>>> For example, the authority responsible for the domain “example.com” could mint the following recognizable Skolem IRI:
>>> 
>>> http://example.com/.well-known/SteveH/d26a2d0e98334696f4ad70a677abc1f6
>>> 
>>> Note: “SteveH” is a placeholder. Names currently under discussion are “genid”, “bnode”, “skolem”.
>>> 
>>> Note: RFC 5758 only specifies well-known URIs, not IRIs. For the purpose of this document, a well-known IRI is any IRI that results in a well-known URI after IRI-to-URI mapping [RFC3987].
>>> 
>>> 
>> 
>> 
>> ----
>> Ivan Herman, W3C Semantic Web Activity Lead
>> Home: http://www.w3.org/People/Ivan/
>> mobile: +31-641044153
>> PGP Key: http://www.ivan-herman.net/pgpkey.html
>> FOAF: http://www.ivan-herman.net/foaf.rdf
>> 
>> 
>> 
>> 
>> 
>> 
> 


----
Ivan Herman, W3C Semantic Web Activity Lead
Home: http://www.w3.org/People/Ivan/
mobile: +31-641044153
PGP Key: http://www.ivan-herman.net/pgpkey.html
FOAF: http://www.ivan-herman.net/foaf.rdf
Received on Thursday, 12 May 2011 14:15:40 GMT

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