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On 9/16/13 2:05 AM, Meehan, Thomas wrote: > 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. Can you say more about what you mean by "redefinition for every element"? kc > > 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] -- Karen Coyle [log in to unmask] http://kcoyle.net m: 1-510-435-8234 skype: kcoylenet