Don: As I understand it, the open world view implies knowledge not asserted for whatever reason, whereas sometimes a negative is a definite (and ultimately verifiable) fact, such as a painting simply not having a title. I think you're ultimately right about unknown things.

Esmé's solution does seem to work, although would perhaps require redefinition for every element (title, place of pub, presence of clasp, binding, etc.). I did wonder if a more generic method existed.

Thank you,

Tom


---

Thomas Meehan
Head of Current Cataloguing
Library Services
University College London
Gower Street
London WC1E 6BT

[log in to unmask]


> -----Original Message-----
> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of
> Donald Brower
> Sent: 13 September 2013 14:46
> To: [log in to unmask]
> Subject: Re: [CODE4LIB] Expressing negatives and similar in RDF
> 
> At a theoretical level, doesn't the Open World Assumption in RDF rule out
> outright negations? That is, someone else may know the title, and could
> assert it in a separate RDF document. RDF semantics seem to conflate
> unknown with nonexistent.
> 
> Practically, Esme's approach seems better in these cases.
> 
> 
> -Don
> 
> 
> --
> Donald Brower, Ph.D.
> Digital Library Infrastructure Lead
> Hesburgh Libraries, University of Notre Dame
> 
> 
> 
> 
> On 9/13/13 8:51 AM, "Esmé Cowles" <[log in to unmask]> wrote:
> 
> >Thomas-
> >
> >This isn't something I've run across yet.  But one thing you could do
> >is create some URIs for different kinds of unknown/nonexistent titles:
> >
> >example:book1 dc:title example:unknownTitle
> >example:book2 dc:title example:noTitle
> >etc.
> >
> >You could then describe example:unknownTitle with a label or comment to
> >fully describe the states you wanted to capture with the different
> >categories.
> >
> >-Esme
> >--
> >Esme Cowles <[log in to unmask]>
> >
> >"Necessity is the plea for every infringement of human freedom. It is
> >the  argument of tyrants; it is the creed of slaves." -- William Pitt,
> >1783
> >
> >On 09/13/2013, at 7:32 AM, "Meehan, Thomas" <[log in to unmask]>
> wrote:
> >
> >> Hello,
> >>
> >> I'm not sure how sensible a question this is (it's certainly
> >>theoretical), but it cropped up in relation to a rare books
> >>cataloguing discussion. Is there a standard or accepted way to express
> >>negatives in RDF? This is best explained by examples, expressed in mock-
> turtle:
> >>
> >> If I want  to say this book has the title "Cats in RDA" I would do
> >>something like:
> >>
> >> example:thisbook dc:title "Cats in RDA" .
> >>
> >> Normally, if a predicate like dc:title is not relevant to
> >>example:thisbook I believe I am right in thinking that it would simply
> >>be missing, i.e. it is not part of a record where a set number of
> >>fields need to be filled in, so no need to even make the statement.
> >>However, there are occasions where a positively negative statement
> >>might be useful. I understand OWL has a way of managing the statement
> >>This book does not have the title "Cats in RDA" [1]:
> >>
> >> []  rdf:type owl:NegativePropertyAssertion ;
> >>     owl:sourceIndividual   example:thisbook ;
> >>     owl:assertionProperty  dc:title ;
> >>     owl:targetIndividual   "Cats in RDA" .
> >>
> >> However, it would be more useful, and quite common at least in a
> >>bibliographic context, to say "This book does not have a title".
> >>Ideally
> >>(?!) there would be an ontology of concepts like "none", "unknown", or
> >>even "something, but unspecified":
> >>
> >> This book has no title:
> >> example:thisbook dc:title hasobject:false .
> >>
> >> It is unknown if this book has a title (sounds undesirable but I can
> >>think of instances where it might be handy[2]):
> >> example:thisbook dc:title hasobject:unknown .
> >>
> >> This book has a title but it has not been specified:
> >> example:thisbook dc:title hasobject:true .
> >>
> >> In terms of cataloguing, the answer is perhaps to refer to the rules
> >>(which would normally mandate supplied titles in square brackets and
> >>so
> >>forth) rather than use RDF to express this kind of thing, although the
> >>rules differ depending on the part of description and, in the case of
> >>the kind of thing that prompted the question- the presence of clasps
> >>on rare books- there are no rules. I wonder if anyone has any more
> >>wisdom on this.
> >>
> >> Many thanks,
> >>
> >> Tom
> >>
> >> [1] Adapted from
> >>http://www.w3.org/2007/OWL/wiki/Primer#Object_Properties
> >> [2] No many tbh, but e.g. title in an unknown script or
> >>indecipherable hand.
> >>
> >> ---
> >>
> >> Thomas Meehan
> >> Head of Current Cataloguing
> >> Library Services
> >> University College London
> >> Gower Street
> >> London WC1E 6BT
> >>
> >> [log in to unmask]