All
My first point when discussing this with Tom was that there seems to be an
inconsistency in the way dct:coverage is defined.
dct:coverage and its sub-properties dct:spatial and dct:temporal include
the subject aspect of their semantic in the definition. But this is not the
case with any other dct attribute. For example, dct:language has definition
"A language of the resource.", not "The language topic of the resource, or
a language of the resource."
This is not inconsistent, however, if we propose that the definition of
dct:coverage is intended to be entirely subsumed by the definition of
subject. That is, "the spatial applicability of the resource, or the
jurisdiction under which the resource is relevant" is intended to refer to
the topicality or "aboutness" of the resource; the spatial applicability
and jurisdiction are assumed to be spatial topics of the resource.
This appears to be supported by Karen's observation "if your map is coded
with geographical coordinates for Berkeley, California, can you consider
Berkeley, California the subject of the map? I think many people would." I
expect similar arguments to be made for jurisdiction: that the geographical
applicability of legislation is "about" that geographical entity.
This implies:
dct:coverage rdfs:subPropertyOf dct:subject .
Then:
dct:spatial rdfs:subPropertyOf dct:coverage .
dct:temporal rdfs:subPropertyOf dct:coverage .
entails:
dct:spatial rdfs:subPropertyOf dct:subject .
dct:temporal rdfs:subPropertyOf dct:subject .
But the definitions of dct:spatial ("Spatial characteristics of the
resource") and dct:temporal ("Temporal characteristics of the resource")
are consistent with dct:language, and we don't generally want to say:
dct:language rdfs:subProperty dct:subject .
A document in a written language is not "about" that language, etc.
This tends to suggest that the proposition that dct:coverage is a
sub-property of dct:subject by virtue of its intended (but possibly
unclear) definition is incorrect. That is, dct:coverage has a scope beyond
"aboutness".
This results in a problem for applications requiring an index of all
subjects/topics "about" a resource. A subject index needs to cover the
objects of triples using dct:coverage, dct:spatial, and dct:temporal, as
well as dct:subject, and will thus include values which are not "about" the
resource (i.e. false drops).
And the same problem will arise when mapping elements from other
bibliographic namespaces to dct.
Cheers
Gordon
On 25 February 2012 at 14:15 Karen Coyle <[log in to unmask]> wrote:
> On 2/24/12 6:38 PM, Thomas Baker wrote:
>
> >
> > To be clear, the definition of dc:subject would remain unchanged: "The
topic of
> > the resource". No definitions would change. The change I am proposing
is that
> > the usage guideline -- that Coverage be used instead of Subject to
describe the
> > spatial or temporal topic of the resource -- be dropped.
> >
> > This does not mean that anyone would have to change what they are doing
--
> > e.g., to start using Subject for describe spatial or temporal topics
instead of
> > Coverage. However, it is not incorrect to use Subject with a spatial
or
> > temporal topic, and removing the usage guideline would remove any
ambiguity in
> > this regard.
>
> But aren't the guidelines "guidelines" not rules? The question is not
> what is or isn't in the guidelines, but what we think is the best
practice.
>
> Note that the *definition* of dc:coverage includes spatial and temporal
> *topics*. Are you saying that you wish for there to be two options for
> spatial and temporal topics? I think that removing the usage guideline
> means the answer to that is "yes." So I ask: is that a good idea?
>
> I also think that because the definition of dc:coverage explicitly
> states spatial and temporal topics, without some explanation there is
> increased ambiguity when the guideline is removed.
>
> kc
>
> >
> > Tom
> >
>
> --
> Karen Coyle
> [log in to unmask] http://kcoyle.net
> ph: 1-510-540-7596
> m: 1-510-435-8234
> skype: kcoylenet
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