On 9/17/13 1:14 AM, Meehan, Thomas wrote:
> Karen,
>
> Yes, I mean that if you have something like:
>
> - example:book1 dc:title example:unknownTitle .
> - example:book2 dc:title example:noTitle .
Thomas, this does not work because the object of dc:title is the title
of the work (actually, the defintion is "A name given to the resource".)
Therefore, you have just declared the title of the work to be
"example:unknownTitle." That obviously isn't right, but most importantly
it isn't helpful. It isn't just a question of dcterms requiring a
literal, it has to do with the meaning of dc:title. You need a property
with a different meaning.
If you do this, then most dc-aware programs would display:
Title: example:unknownTitle
It would actually probably be more useful to say:
dc:title "unknown title"
although again you would be declaring that string to be the actual title
of the item, which then gets us into the "Title varies" issue -- that
is, you cannot prevent someone from creating a resource and giving it
the actual title "unknown title."
Now, if you were to have the object of dc:title defined as "Content as
Text", then, as the conversation continued between Esme and I, you could
have a blank text (which would be saying that dc:title = ""), and, since
the object of dc:title would be a URI (not a string), you could
potentially mint a new property with the semantics of "title status"
that could take an object like "example:unknownTitle."
kc
> "
>
> 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
>
> [log in to unmask]
>
>> -----Original Message-----
>> From: Code for Libraries [mailto:[log in to unmask]] On Behalf Of
>> Karen Coyle
>> Sent: 16 September 2013 16:23
>> To: [log in to unmask]
>> 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
>>>
>>> [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
--
Karen Coyle
[log in to unmask] http://kcoyle.net
m: 1-510-435-8234
skype: kcoylenet
|
