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Re: semantics of daml:UnambiguousProperty

From: Ian Horrocks <horrocks@cs.man.ac.uk>
Date: Thu, 25 Jan 2001 10:07:24 +0000 (GMT)
Message-ID: <14959.64220.584650.276504@excalibur.cs.man.ac.uk>
To: Dan Brickley <danbri@w3.org>
Cc: <www-rdf-logic@w3.org>
All inferences justified by the DAML+OIL semantics reflect a snapshot
of the state of the world (web) at that moment. The logic is
monotonic, so adding information will not invalidate existing
inferences, but changing/removing information might do.


On January 23, Dan Brickley writes:
> A little question re DAML+OIL semantics. If a property is an unambigous
> property, does the equality specified by DAML+OIL below hold only at a
> particular point in time or does it hold across time and change?
> Eg. if I say some resource X has a foo:contact property
> whose value is some other resource Y, where Y is "the resource  whose
> personalMailbox is mailto:lighthouse-keeper@stonyisland.example.com", what
> does this mean? Might Y differ over time, so long as at any one time there
> was only a single resource with that property/value pair. What inferences
> does daml:UnambiguousProperty license in this respect?
> Dan
> http://www.daml.org/2000/12/daml+oil.daml
> <rdfs:Class rdf:ID="UnambiguousProperty">
>   <rdfs:label xml:lang="en">UnambiguousProperty</rdfs:label>
>   <rdfs:comment>
>     if P is an UnambiguousProperty, then if P(x, y) and P(z, y) then x=z.
>     aka injective. e.g. if nameOfMonth(m, "Feb")
>     and nameOfMonth(n, "Feb") then m and n are the same month.
>   </rdfs:comment>
>   <rdfs:subClassOf
> rdf:resource="http://www.w3.org/1999/02/22-rdf-syntax-ns#Property"/>
> </rdfs:Class>
> http://www.daml.org/2000/12/reference.html
>        an UnambigousProperty element.
>        This asserts that an instance y can only be the value of P for a
> single instance x, i.e: there cannot be two distinct instances x1 and x2
> such that both (x1,y) and
>        (x2,y) are both instances of P.
Received on Thursday, 25 January 2001 05:41:45 UTC

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