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Re: Lexing RIF PS

From: Axel Polleres <axel.polleres@deri.org>
Date: Tue, 23 Sep 2008 18:54:54 +0100
Message-ID: <48D92D6E.5020309@deri.org>
To: Hassan Ait-Kaci <hak@ilog.com>
CC: RIF WG <public-rif-wg@w3.org>

Hassan Ait-Kaci wrote:
> Hi Axel,
> 
> Thanks for your reply.
> 
> No, I am not suggesting that RIF not support relative IRI's in the PS. 
> However,
> instead of relying on implicit IRI structure, why not introduce a simple way
> of recognizing such IRI's? What I have right now is an ad hoc way of 
> doing so
> - basically when reading the sequence of chars that make up a string, if it
> starts with a dot, then it is lexed as a relative IRI. The examples you give
> abide by this, but I have no clue whether this flies as a safe approximation
> in general. A simpleri and safer possiblity may be to introduce an explicit
> lexical marker to identify relative IRI's in the same way we recognize local
> names (using a '_' at the beginning.

I am admittedly reluctant here, since this sounds to be against the use 
of relative URIs in other specs. Other opinions?

Axel

> -hak
> --
> Hassan At-Kaci  *  ILOG, Inc. - Product Division R&D
> http://koala.ilog.fr/wiki/bin/view/Main/HassanAitKaci
> 
> 
> 
> -----Original Message-----
> From: Axel Polleres [mailto:axel.polleres@deri.org]
> Sent: Tue 9/23/2008 7:27 PM
> To: Hassan Ait-Kaci
> Cc: RIF WG
> Subject: Re: Lexing RIF PS
> 
> 
>  > This, unfortunately again, requires that any lexical analyzer for the
>  > RIF PS include complete IRI parser - which I am not willing to invest
>  > any effort in at this nor any near future time.
> 
> Ok, I agree with your assessment that for relative IRI resolution the
> relative IRI needs to be parsed. but do you imply any consequences?
> Do you suggest we don't support relative IRIs?
> 
> Many other standards do, actually, I would be surprised if not
> off-the-shelf libraries were available which support relative IRI/URI
> rsolution.
> 
> Maybe somebody else in the group from the more XML end can add some
> hints here?
> 
> best,
> Axel
> 
> Hassan Ait-Kaci wrote:
>  > Hi Axel,
>  >
>  > Still in the process of deciphering the intricacies of what
>  > constitutes a RIF BLD/DTB lexical unit, I have a question for you
>  > regarding how you describe the RIF symbol spaces, and specifically
>  > the use of the Base directive to expand on relative IRI's.
>  >
>  > In http://www.w3.org/TR/2008/WD-rif-dtb-20080730/#Relative_IRIs,
>  > you describe how the Base directive (at most one per RIF document)
>  > can be used to declare a base IRI for resolving relative IRI's
>  > in RIF. You wrote:
>  >
>  >  > 2.1.3 Relative IRIs
>  >  >
>  >  > Relative IRIs in RIF documents are resolved with respect to the base
>  >  > IRI. Relative IRIs are combined with base IRIs as per Uniform
>  >  > Resource Identifier (URI): Generic Syntax [RFC-3986] using only the
>  >  > basic algorithm in Section 5.2.
>  >
>  > You go on giving the following examples :
>  >
>  >  > For instance, the constant <./xyz> or "./xyz"^^rif:iri are both
>  >  > valid abbreviations for the constant
>  > "http://www.example.org/xyz"^^rif:iri
>  >  > in a RIF document in presentation syntax that has the single base
>  >  > directive Base( http://www.example.org ) in its preamble.
>  >
>  > Basically, the above entails that the internal structure of IRI's
>  > must be parsed out of all RIF PS string constants and identifiers
>  > that happen to be legal IRI's.  At least this is what I understand
>  > from the avove and reference you cite [RFC 3986, Berners-Lee, et al.,
>  > January 2005, Standards Track, Page 25, (URI Generic Syntax)], which
>  > states:
>  >
>  >  > 4.1.  URI Reference
>  >  >
>  >  >    URI-reference is used to denote the most common usage of a resource
>  >  >    identifier.
>  >  >
>  >  >       URI-reference = URI / relative-ref
>  >  >
>  >  >    A URI-reference is either a URI or a relative reference.  If the
>  >  >    URI-reference's prefix does not match the syntax of a scheme 
> followed
>  >  >    by its colon separator, then the URI-reference is a relative
>  >  >    reference.
>  >  >
>  >  >    A URI-reference is typically parsed first into the five URI
>  >  >    components, in order to determine what components are present and
>  >  >    whether the reference is relative.
>  >
>  > This, unfortunately again, requires that any lexical analyzer for the
>  > RIF PS include complete IRI parser - which I am not willing to invest
>  > any effort in at this nor any near future time.
>  >
>  > -hak
>  > --
>  > Hassan At-Kaci  *  ILOG, Inc. - Product Division R&D
>  > http://koala.ilog.fr/wiki/bin/view/Main/HassanAitKaci
>  >
>  >
>  >
> 
> 
> --
> Dr. Axel Polleres, Digital Enterprise Research Institute (DERI)
> email: axel.polleres@deri.org  url: http://www.polleres.net/
> 
> Everything is possible:
> rdfs:subClassOf rdfs:subPropertyOf rdfs:Resource.
> rdfs:subClassOf rdfs:subPropertyOf rdfs:subPropertyOf.
> rdf:type rdfs:subPropertyOf rdfs:subClassOf.
> rdfs:subClassOf rdf:type owl:SymmetricProperty.
> 
> 
> 


-- 
Dr. Axel Polleres, Digital Enterprise Research Institute (DERI)
email: axel.polleres@deri.org  url: http://www.polleres.net/

Everything is possible:
rdfs:subClassOf rdfs:subPropertyOf rdfs:Resource.
rdfs:subClassOf rdfs:subPropertyOf rdfs:subPropertyOf.
rdf:type rdfs:subPropertyOf rdfs:subClassOf.
rdfs:subClassOf rdf:type owl:SymmetricProperty.
Received on Tuesday, 23 September 2008 17:55:43 GMT

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