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
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m: 1-510-435-8234
skype: kcoylenet