Re: rdf as a base for other languages

From: Sandro Hawke <sandro@w3.org>
Subject: Re: rdf as a base for other languages
Date: Fri, 01 Jun 2001 13:47:10 -0500

> In message <20010601130755B.pfps@research.bell-labs.com> you wrote:
> 
> >For example, suppose that you wanted to represent propositional formulae
> >within RDF.  You might do something like:
> >
> ><rdf:type x OR>
> ><component x y>
> ><component x z>
> >
> ><rdf:type y rdf:Statement>
> ><rdf:subject y John>
> ><rdf:predicate y loves>
> ><rdf:object y Mary>
> >
> ><rdf:type z rdf:Statement>
> ><rdf:subject z John>
> ><rdf:predicate z loves>
> ><rdf:object z Susan>
> >
> ><loves Bill Susan>
> >
> ><rdf:type Bill Person>
> ><rdf:type John Person>
> ><rdf:type Susan Person>
> ><rdf:type Mary Person>
> >
> >You understand this collection of RDF triples to mean that Bill loves
> >Susan and John loves either Mary or Susan, and that they are all people.
> 
> Well, not really.  I had to think about which kind of OR you meant.
> Did you you mean to just declare a relation (r=y OR z) or did you mean
> to assert something (true=y OR z)?  I (with help from Eric
> Prud'hommeaux looking over my shoulder) made a closed-world
> assumption, noting the absense of <result x r>, and decided you meant
> the later version.
> 
> The two kinds of OR are exactly like my two kinds of robot actions:
> does it jump when I tell it about a jump, or does it wait until I
> specifically ask it to perform the jump?
> 
> The point is that some RDF vocabular terms need to be defined as
> "operational" or "performative" for particular agents.  Your OR was a
> performative OR, where the operation was to add a disjunction to the
> knowledge base obtained by reading the text.  That operation could
> only be performed by an agent which understands disjunction, of
> course.
> 
>     -- sandro

I don't understand where operational or performative fits in here.  I'm not
trying to represent any operations or performances, just represent
formulae.  

What I am trying to present is an attempt to transfer complex logical
constructs within an RDF syntax, and how the way RDF is defined makes this
problematic.  No operations, no performances, and not even any
inferences---just collections of logical formulae (with an implicit
conjunction).  There is no attempt to require that an agent ``add'' a
disjunction, the agent is allowed to do whatever it wants, as long as it
understands that the collection of RDF triples are only consistent with
logical models where the disjunction is, indeed, true.

peter

Received on Friday, 1 June 2001 17:13:00 UTC