Karen, Yes, I mean that if you have something like:
- example:book1 dc:title example:unknownTitle . - example:book2 dc:title example:noTitle . then this approach only works for the dc:title element (putting aside for now what you said about dc:title requiring a literal). For any other elements you would need to define a similar example:unknownThing: - example:book2 example:claspNote "brass" . - example:book2 example:claspNote example:noClasp . The same would go for the following approach: - example:book2 example:hasATitle egboolean:false . - example:book2 example:hasAClasp egboolean:false . I hope these make sense. An approach that could be used for any element might be useful. I admit at this stage that I need to reread the second half of the thread again. I can't decide in my head if this is something that the rules (RDA, etc) should handle. If so, RDA in particular has an entertaining variety of ways of doing so. Thanks, Tom --- Thomas Meehan Head of Current Cataloguing Library Services University College London Gower Street London WC1E 6BT t.mee...@ucl.ac.uk > -----Original Message----- > From: Code for Libraries [mailto:CODE4LIB@LISTSERV.ND.EDU] On Behalf Of > Karen Coyle > Sent: 16 September 2013 16:23 > To: CODE4LIB@LISTSERV.ND.EDU > Subject: Re: [CODE4LIB] Expressing negatives and similar in RDF > > 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 > > > > t.mee...@ucl.ac.uk > > > > > >> -----Original Message----- > >> From: Code for Libraries [mailto:CODE4LIB@LISTSERV.ND.EDU] On Behalf > >> Of Donald Brower > >> Sent: 13 September 2013 14:46 > >> To: CODE4LIB@LISTSERV.ND.EDU > >> 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" <escow...@ucsd.edu> 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 <escow...@ucsd.edu> > >>> > >>> "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" <t.mee...@ucl.ac.uk> > >> 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 > >>>> > >>>> t.mee...@ucl.ac.uk > > -- > Karen Coyle > kco...@kcoyle.net http://kcoyle.net > m: 1-510-435-8234 > skype: kcoylenet
