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The message quoted below was sent to my private adress rather than the list,
I really hope no offense is taken when I feed it back to the list, especially
since my answer also tries to address Ray Denenberg's remark about objections
to the bf:uri property.
Am 17.07.2014 00:01, schrieb Karen Coyle:
>
> On 7/16/14, 1:45 PM, Thomas Berger wrote:
>> Listing strings and URIs (perhaps not as identifierValue but
>> as an hypothetic identifierURI) within the same container is
>> not contradictory on a formal level, I think.
> The problem there was precisely addressed in:
>
> http://listserv.loc.gov/cgi-bin/wa?A2=ind1407&L=bibframe&T=0&P=8029
>
> As Rob says there, and Ray and Kevin concur, it is a problem if the same URI is
> used to represent more than one thing. I would expect reasoners to choke on this
> as an inconsistency.
>
> It is NOT a problem to have multiple URIs for the SAME thing, and, sure, you can
> say that they are the same identifier in a different form. But you should not
> expect to use a URI both as an object of the property bf:identifier and as a RWO.
Sure. But Rob's (absolutely valid) point are the inconsistencies arising
from resource URIs we want to distinguish as "identifiers" simultaneously
used as resource URI for the bf:Identifier as such. Making statements about
some URIs (as URIs as in contrast to the resources they represent) would
constitute a more subtle form of the same(?) fallacy and is likewise absolutely
not admissible.
My point of view however would be to simply dispense n URIs into m bf:Identifier
containers and keep them striclty in object position there...
We could write
<http://www.example.org/xyz>
a bf:Instance;
... our description ... ;
owl:sameAs <urn:isbn:1-2-3>, <info:isbn/1234> .
but this really are just two odd URIs we additionally provide. To conclude
any connection with the ISBN system is a delusion arising from the fact that
we humans cannot resist interpreting URIs and charging them with meaning we
strive to detect in their string representation (Imagine this was an HTML
formatted mail and I would provide a QR code instead of a string between the
angle brackets.)
On the other hand a graph
<http://www.example.org/xyz>
a bf:Instance;
... our description ... ;
bf:identifier [
a bf:Identifier,
bf:identifierScheme "ISBN",
bf:identifierValue "978-1-2-3",
bf:identifierValueURI <urn:isbn:978-1-2-3>, <info:isbn/123> .
] .
would assert that within the semantic context of "ISBN"
the two URIs provided
a) "make sense" (meet a certain consensus about admissible
denominations) [or is this already a fallacious statement
/about/ the URIs as such?]
and b) their corresponding resources are equivalent to
our resource
and therefore c) their corresponding resources are
the same.
This still does not open the URIs given to analysis or algorithmic
transformations but at least establishes their "ISBN" context.
Alternatively we (not RDF) could transform the URIs into literals and
state
<http://www.example.org/xyz>
a bf:Instance;
... our description ... ;
bf:identifier [
a bf:Identifier,
bf:identifierScheme "ISBN",
bf:identifierValue "978-1-2-3",
bf:identifierValueURIasString "urn:isbn:1-2-3", "info:isbn/1234" .
] .
These strings cannot be used as URIs any more but instead are open
to inspection and algorithmic transformations.
Usage of identifierValueURIasString instead of a plain identifierValue
would indicate that this literal could be turned into an URI by
mechanisms outside of RDF. The distrinction would be simply for the
convenience of the human reader...
Technically the basic thing we need our (real world, traditional)
identifiers for is comparison (the real world tasks like "hunting
down" I mentioned before are dealt with differently in semantic web
contexts), but preferably according to the rules of the scheme
they are taken from. For the three forms given in the example
already we are stating their identity thus both versions serve our
need. For other forms we may encounter in different graphs
we could employ an hypothetical, "ISBN"-specfic canonicalization
service of our choice - and perhaps it is more feasible to encode
strings as parameters in URL construction for that service
than URIs.
As mentioned the string "ISBN" as value for bf:identifierScheme
is not a favorable way of fixating the scheme. Bibframe also provides
the "isbn" subproperty with isbn10 and isbn13 sub-subproperties
The official example
<http://id.loc.gov/resources/bibs/17082740> a bf:Work ;
bf:hasInstance [ a bf:Instance ;
bf:isbn13 <http://isbn.example.org/9780738609089> ] .
does not tell us about the ISBN as a real world identifier,
we'll have to resort to <http://isbn.example.org/9780738609089>
(read: <http://my.volatile.private.isbn.identifier.store.example.org>)
first and may see there:
<http://isbn.example.org/9780738609089> a bf:Identifier ;
bf:identifierScheme "ISBN";
bf:identifierValue "978-0-7386-0908-9".
Or combined and restated the preferred way with an anonymous node:
<http://id.loc.gov/resources/bibs/17082740> a bf:Work ;
bf:hasInstance [ a bf:Instance ;
bf:isbn13 [ a bf:Identifier ;
bf:identifierScheme "ISBN";
bf:identifierValue "978-0-7386-0908-9".]
] .
By using the bf:isbn13 property our bf:Instance very strictly
"knows" what kind of identifier it is referring to, however
the identifier resource as such just vaguely performs an
incantation of "ISBN": IMHO a grave deficiency of the current
design.
Can this be remedied by also admitting the bibframe vocabulary for
the subproperties as range for bf:identifierScheme instead of
literals?
<http://isbn.example.org/9780738609089> a bf:Identifier ;
bf:identifierScheme bf:isbn;
bf:identifierValue "978-0-7386-0908-9".
yielding
<http://id.loc.gov/resources/bibs/17082740> a bf:Work ;
bf:hasInstance [ a bf:Instance ;
bf:isbn13 [ a bf:Identifier ;
bf:identifierScheme bf:isbn;
bf:identifierValue "978-0-7386-0908-9".]
] .
Or maybe the other way round:
<http://id.loc.gov/resources/bibs/17082740> a bf:Work ;
bf:hasInstance [ a bf:Instance ;
bf:isbn [ a bf:Identifier ;
bf:identifierScheme bf:isbn13;
bf:identifierValue "978-0-7386-0908-9".]
] .
or more generic
<http://id.loc.gov/resources/bibs/17082740> a bf:Work ;
bf:hasInstance [ a bf:Instance ;
bf:identifier [ a bf:Identifier ;
bf:identifierScheme bf:isbn13;
bf:identifierValue "978-0-7386-0908-9".]
] .
However ISBN-10/ISBN-13 issues are peculiar to the ISBN system
requiring a more thorough discussion I do not deem appropriate
in this thread.
viele Gruesse
Thomas Berger
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