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RE: SWRL string builtins -- suggestion

From: Neil Goldman <ngoldman@teknowledge.com>
Date: Thu, 3 Jun 2004 12:59:48 -0700
Message-ID: <E7E360AA6A3EC74C81C4D48B9F901DBB256897@helium.teknowledge.com>
To: <massimo@w3.org>
Cc: <www-rdf-rules@w3.org>

Minor correction --In the very particular case of this discussion, fn:substring appears to be irrelevant 
(it is analagous to  swrlb:substring in the SWRL document.)

fn:string-to-codepoints and fn:codepoints-to-string provide mappings between strings and charater codes.


neil

> -----Original Message-----
> From: massimo@w3.org [mailto:massimo@w3.org]
> Sent: Thursday, June 03, 2004 7:12 AM
> To: Neil Goldman
> Cc: www-rdf-rules@w3.org
> Subject: RE: SWRL string builtins -- suggestion
> 
> 
> All this is a very small subpart of the much more general issue,
> not just belonging to SWRL but to Semantic Web 
> Query/Reasoning in general,
> of selecting/reusing a common suitable set of functions and operators.
> Cf. from the Conclusions in 
> http://www.w3.org/Submission/2004/03/Comment:
> <quote>
> understanding that graceful interoperation within the RDF 
> model and with
> the XQuery functions and operators may well be the key to the 
> success of
> components of the Semantic Web.
> </quote>
> 
> So, the more general issue is, rather then reinventing the wheel,
> trying to find the common set that applications can 
> understand/share/reuse.
> Obvious candidate for analysis: http://www.w3.org/TR/xpath-functions/
> 
> As said, this is not much of an SWRL issue, but of any Web 
> Query/Reasoning
> application that wants to gracefully scale.
> 
> -M
> 
> ps In the very particular case of this discussion, 
> fn:substring would do
> what you want.
> 
> 
> 
> >
> > I'm not sure what sort of abuse of a "charat" relation you 
> are worried
> > about, but certainly such abuse must already be possible via
> > swrlb:substring, which allows one-character substrings to 
> be referenced
> > via rules.
> >
> > My feeling is that since OWL has adopted the XML schema 
> standard datatype
> > "string" it is unreasonable to place part of that standard 
> outside the
> > scope of "rules" SOLELY because it might be misused.  It is 
> clear that the
> > standard (quoted below) makes a "charat" relation well defined.  Any
> > application program that obtains a  string value from OWL 
> can readily
> > obtain the integer codes of the individual charcters of 
> that string with
> > trivial library APIs available in every programming langauge.  My
> > suggestion is simply that the built-ins of a rules standard 
> should cover
> > this aspect of the string type.
> >
> > In any case, we should not think of the type "string" as 
> synonymous with
> > "natural language text".  Strings are also used to 
> represent fragments of
> > programming language source code and network protocols and 
> passwords and
> > DNA codes and many other things which are not natural 
> language at all.
> >
> > ===========from http://www.w3.org/TR/2000/WD-xmlschema-2-20000225
> > 3.2.1 string
> > [Definition:]  The string datatype represents character 
> strings in XML.
> > The value space of string is the set of finite sequences of 
> UCS characters
> > ([ISO 10646] and [Unicode]). A UCS character (or just character, for
> > short) is an atomic unit of communication; it is not 
> further specified
> > except to note that every UCS character has a corresponding UCS code
> > point, which is an integer. The ordered property of string is the
> > [Unicode] character number sequence
> >
> >> -----Original Message-----
> >> From: Martin Duerst [mailto:duerst@w3.org]
> >> Sent: Monday, May 31, 2004 1:07 AM
> >> To: Neil Goldman; www-rdf-rules@w3.org
> >> Cc: Neil Goldman
> >> Subject: Re: SWRL string builtins -- suggestion
> >>
> >>
> >> This may be a bad idea. In English, a lot of functions on strings
> >> can be implemented by using functions on individual characters of
> >> the string. So a 'charAt' function seems very tempting. But in
> >> many other languages, things are not as simple as that. Of course
> >> this depends on the operation and the language.
> >>
> >> Regards,    Martin.
> >>
> >> At 16:45 04/05/28 -0700, Neil Goldman wrote:
> >>
> >> >I believe the string builtins should provide a means to get to an
> >> >individual character, not just to a string of length 1.
> >> >It would suffice to provide:
> >> >
> >> >swrlb:charAt
> >> >Satisfied iff the first argument is equal to the character
> >> code of the
> >> >character in the string second argument appearing at index
> >> third argument
> >> >
> >> >====================> >
> >> >Neil Goldman              Tel:   (310)578-5350 x204
> >> >Teknowledge Corporation   Fax:   (310)578-5710
> >> >Suite 1010
> >> >4640 Admiralty Way
> >> >Marina del Rey, CA 90292
> >>
> >>
> >>
> >
> 
> 
> 
Received on Thursday, 3 June 2004 16:01:26 GMT

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