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Hi Tom, I think it comes down to what you really mean by a book not having a title. A few options I can think of: 1) This book was published without a title (or whatever verb you want there if you want to cover unpublished material) 2) The author did not give this work a title 3) I've never heard of anyone calling this work by a formal title There are certainly lots more options for a definition of untitled. But if you're thinking along the lines of #3, I agree the open world assumption comes into play, and you just done have a triple with a title-like property, and if someone somewhere else has one, great. If #1 or #2 or anything similar in structure, how about declaring titleless-ness as a class that's a subclass of book? The semantics there would be "books published without titles" or "books not given titles by their authors" or whatever. You'd then just have a triple declaring this book part of that class. Or the titleless-ness class could be broader than just books, and a subclass of creative work (as defined in your vocabulary of choice). Jenn -------------------------------- Jenn Riley Head, Carolina Digital Library and Archives The University of North Carolina at Chapel Hill http://cdla.unc.edu/ http://www.lib.unc.edu/users/jlriley [log in to unmask] (919) 843-5910 On 9/13/13 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]