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
