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Re: Semantic E-mail

From: Laurian Gridinoc <laurian@gmail.com>
Date: Thu, 15 Jul 2004 13:20:27 +0000
Message-ID: <9782e335040715062075170a42@mail.gmail.com>
To: www-rdf-interest@w3.org
Cc: danny@dannyayers.com

On Thu, 15 Jul 2004 14:01:33 +0200, Danny Ayers <danny666@virgilio.it> wrote:
> >>If the other terms really are equivalent then you could use
> >>owl:equivalentProperty, but then why bother creating a new term when you
> >>could use an equivalent?
> >
> >"Property equivalence is not the same as property equality.
> >Equivalent properties have the same "values" (i.e., the same property
> >extension), but may have different intensional meaning (i.e., denote
> >different concepts). Property equality should be expressed with the
> >owl:sameAs construct. As this requires that properties are treated as
> >individuals, such axioms are only allowed in OWL Full." [1]
> >
> >This is what I'm trying to avoid - OWL Full.
> 
> Then don't use owl:sameAs.
> This doesn't prevent you from using an existing equivalent or
> owl:equivalentProperty.
> Look at some individuals:
> 
> {1}
> m1 filsa:messageid "Message One"
> m2 filsa:messageid "Message Two"
> m3 filsa:messageid "Message Three"
> 
> if you said
> {2}
> new:messageId owl:equivalentProperty filsa:messageid
> 
> then you could infer -
> {3}
> m1 new:messageId "Message One"
> m2 new:messageId "Message Two"
> m3 new:messageId "Message Three"

yes,  "Message One" is then a value of `filsa:messageid'; but this
does not imply that the statement `m1 new:messageId "Message One"'
have the same meaning as `m1 new:messageId "Message One"'

> btw, I suspect the actually aspect of owl:sameAs you'd be using in
> practice is the above,  the result of the entailment:
> p1 rdf:type rdf:Property
> p2 rdf:type rdf:Property
> p1 owl:sameAs p2
> =>
> p1 owl:equivalentProperty p2

yes, but owl:equivalentProperty is a generalization of owl:sameAs,
since it says that  p1 and p2 have the same values, not meaning.
 
> Anyhow, if there wasn't a one-to-one match between the sets of
> individuals, then you could say:
> {4}
> new:messageId rdfs:subPropertyOf filsa:messageid
> but then you couldn't infer {3} from {1}, although you could infer {1}
> from {3}

agree, I'm after {1} from {3}, more precisely after the meaning of {1}
from {3} not equivalence.

> you could swap it around, so new:messageId was the more general
> property, but it depends on what the semantics actually are, what you're
> trying to capture...

owl:sameAs :)
 
> >I would prefer to stay with the most simple solution - RDF(S), worst
> >case lightest OWL possible; but Josh Sled pointed that owl:sameAs
> >applied to classes or properties is OWL Full.
> 
> Those are really conflicting requirements - if you want to stay within
> OWL DL then you will need more qualification of the properties to which
> you refer. The simplest you could possibly do would be to use
> rdfs:subPropertyOf as above, or if you really want to assert equivalence
> then use -
> 
> p1 rdfs:subPropertyOf p2
> p2 rdfs:subPropertyOf p1
> 
> the combination expresses equivalence of the properties, and an OWL Full
> reasoner could get {3} from {1} and vice versa.

I have thought of this construction, but I'm not sure if it is
considered logical valid, creating a loop in a hierarchy?
 
> >>The volatility issue is tricky - it's a common problem. OWL has
> >>versioning capability terms that could be used to manage this, though
> >>where individual terms may change independently OWL's per-schema
> >>versioning isn't really granular enough. The craftiest solution I've
> >>seen to this came recently from Alistair Miles and Chaals, using a
> >>separate little ontology for each term.
> >
> >Indeed a nice solution, if you can control the schema; which is not
> >the case when you mix vocabularies.
> 
> True, but you can still add a level of indirection:
> 
> foreign vocab :
> their:messageId rdf:type rdf:Property
> 
> {local subschema} :
> my:messageId owl:equivalentProperty their:messageId
> 
> local (namespaced that is used) schema
> import {local subschema}

Same meaning issue as above - my messageId values are also values of
the foreign property; but can I reasoner `get' that they have the same
meaning?
 

Thank you,
-- 
Laurian Gridinoc
Chief Developer
GRAPEFRUIT DESIGN
www.gd.ro
Received on Thursday, 15 July 2004 09:21:06 UTC

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