RE: Lexing RIF PS

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.

-hak
--
Hassan Aït-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 Aït-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.