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Re: owl:sameAs [recipe]

From: Alan Ruttenberg <alanruttenberg@gmail.com>
Date: Mon, 27 Jul 2009 21:47:22 -0400
Message-ID: <29af5e2d0907271847k3deffcb4m935556483cec4ab2@mail.gmail.com>
To: Eric Lease Morgan <eric_morgan@infomotions.com>
Cc: public-lod@w3.org
On Mon, Jul 27, 2009 at 9:23 PM, Eric Lease
Morgan<eric_morgan@infomotions.com> wrote:
> On Jul 25, 2009, at 5:09 AM, Bill Roberts wrote:
>> Regarding linking to external resources, what it seems you want
>> to do is to identify the dc:creator of the book, hence say that
>> the creator is the person whose name was Thomas More. You could
>> create your own URI and if you are managing a whole bunch of data
>> about books and authors, then there could be reasons to do that,
>> but in general if there is a satisfactory existing URI, it is
>> preferable to use it. Dbpedia seems to have become the de facto
>> standard...

I will put in, for the record, a dissenting voice to this recipe,
which I believe does not best serve the semantic web community.
Specifics below

> Okay, then how's this for a recipe to create rich linked data of electronic
> books and authors within my own site as well as to the outside world:
>  1. Mint URIs pointing to representations of local etexts

This one makes sense. There are particular manifestations (in the FRBR
sense) in the form of etexts, that you are providing.

>  2. Mint URIs pointing to representations of authors of local etexts

There is only one instance of an author. If there is an existing URI
for the author - a dbpedia URI, for instance, then I think that should
be used. There is no use for an additional URI, and having them puts
additional strain on every single client that has to manage them.

>  3. In resources of etexts, include owl:sameAs links to DBpedia resources

As I pointed out before, these are not sameAs. The dbpedia resource
are better understood as representing the expression, in the FRBR
sense, and the link from expression to manifestation is not sameAs.

>  4. In resources of etexts, point to local URIs of authors

No, point to already existing URIs of authors. If you have a web page
you wish to provide to give additional information about these
authors, link to that by an assertion
<author> foaf:page <your web page>, or
<author> foaf:primaryTopicOf <your web page>

>  5. In resources of authors, include owl:sameAs links to DBpedia resources

It is not at all clear to me that you need or want additional RDF for
each author, unless you are saying something new about them. If it is
for indexing, then the links go both ways and an aggregator will be
able to follow the link you already established from etext to author.

>  6. In resources of authors, include owl:creatorOf links to local etexts

What is owl:creatorOf? I presume you would have used, in the
representation of the etext,
<etext> dc:creator <dbpedia uri of author>

I am unconvinced, as I say above, that there is any need for you to
create any representation of the author.

>  7. For extra credit, do the same thing for subjects/keywords

Given the direction things are going, I am worried. This deserves
further explication.

> For example, the following resource descriptions:
> <!-- etext #1; points to local author and remote title -->
> <rdf:RDF
>  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>  xmlns:dcterms="http://purl.org/dc/terms/"
>  xmlns:owl="http://www.w3.org/2002/07/owl#"
+  xmlns:frbr = "http://purl.org/vocab/frbr/core#"

>  <rdf:Description
>    rdf:about="http://infomotions.com/etexts/id/more-utopia-221"

-    owl:sameAs="http://dbpedia.org/resource/Utopia_(book)">
+   frbr:embodimentOf="http://dbpedia.org/resource/Utopia_(book)"

>    <dcterms:title>Utopia</dcterms:title>
>    <dcterms:creator
- rdf:resource="http://infomotions.com/etexts/authors/resource/thomas-more" />
+ rdf:resource="http://dbpedia.org/resource/Thomas_More"/>
>  </rdf:Description>

<rdf:description rdf:about="http://infomotions.com/authors/page/thomas-more">
  <foaf:primaryTopic rdf:about="http://dbpedia.org/resource/Thomas_More">

> </rdf:RDF>

ditto for below

> <!-- etext #2; points to local author and remote title -->
> <rdf:RDF
>  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>  xmlns:dcterms="http://purl.org/dc/terms/"
>  xmlns:owl="http://www.w3.org/2002/07/owl#">
>  <rdf:Description
>    rdf:about="http://infomotions.com/etexts/id/more-reality-404"
>    owl:sameAs="http://dbpedia.org/resource/Reality_(book)">
>    <dcterms:title>Reality</dcterms:title>
>    <dcterms:creator
> rdf:resource="http://infomotions.com/etexts/authors/resource/thomas-more" />
>  </rdf:Description>
> </rdf:RDF>

Toss this.

> <!-- author; points to local etexts and remote author -->
> <rdf:RDF
>  xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
>  xmlns:owl="http://www.w3.org/2002/07/owl#">
>  <rdf:Description
>    rdf:about="http://infomotions.com/etexts/authors/resource/thomas-more"
>    owl:sameAs="http://dbpedia.org/resource/Thomas_More">
>    <owl:creatorOf
> rdf:resource="http://infomotions.com/etexts/id/more-utopia-221"/>
>    <owl:creatorOf
> rdf:resource="http://infomotions.com/etexts/id/more-reality-404" />
>  </rdf:Description>
> </rdf:RDF>
> --

Sorry to be critical, but there is an important principle here: First
do no harm. Willy nilly inventing URIs and entities when there are
perfectly good ones in existence is not "cool" from a semweb point of
view, and unnecessary use of sameAs is both burdensome and likely to
lead to gross errors, as I have pointed out in my previous emails.

Received on Tuesday, 28 July 2009 01:48:22 UTC

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