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Re: owl:sameAs [recipe]

From: Kingsley Idehen <kidehen@openlinksw.com>
Date: Wed, 29 Jul 2009 12:35:58 +0100
Message-ID: <4A70341E.3040502@openlinksw.com>
To: Hugh Glaser <hg@ecs.soton.ac.uk>
CC: Eric Lease Morgan <eric_morgan@infomotions.com>, "public-lod@w3.org" <public-lod@w3.org>
Hugh Glaser wrote:
> On 28/07/2009 14:46, "Kingsley Idehen" <kidehen@openlinksw.com> wrote:
>
>   
>> Hugh Glaser wrote:
>>     
>>> Good stuff.
>>> However, I don't think that Named Graphs are the answer.
>>> I get my Linked Data by resolving URIs over http.
>>> If I ask your Linked Data Space (I hope that is the right use of your
>>> terminology) for something like
>>> curl -H "Accept: application/rdf+xml" http://dbpedia.org/resource/London
>>> and follow the redirect don't I still get the non-wikipedia data with the
>>> wikipedia data?
>>> Or am I not understanding something?
>>>  
>>>       
>> The link chain shouldn't be broken. Named Graphs should have zero impact
>> on HTTP URIs.
>>     
> That is what I thought.
> So how is the linkage data kept separate when I do URI resolution?
> Cheers
>   
Hugh,

The Linkage isn't what needs separating.

Its when you make a data set that is 100% entity to entity links 
triples  (i.e., a linkset or linkbase) that needs separating (as good 
practice) from the main KB.  Remember, there are times when the main KB 
and the source of cross links to external entities are produced by 
separate parties. Thus, the linksets end up in their own Named Graphs. 
Purely for organization and maintenance. This kind of partitioning 
allows the use SPARUL scoped to Named Graphs when fixing triple 
statement errors (e.g. owl:sameAs triples), for instance.

Kingsley



>> I think Alan is saying: put what is best described as a linkbase dump in
>> a separate Named Graph. Doing this shouldn't break the tapestry inherent
>> in the HTTP URIs (the data  conductors). We have tons of data in
>> <http://lod.openlinksw.com> partitioned across named graphs, and none of
>> that breaks the "follow-your-nose" pattern. Remember, I am a stickler
>> for keeping the HTTP URIs of entities in full scope of user agents :-)
>>
>> The only time you might have an issue is when performing SPARQL, where
>> explicitly identifying the Named Graph in the FROM Clause may aid
>> performance (and even here this depends on the indexing in placece re,
>> the RDF DBMS insta, these days re. Virtuoso that doesn't even matter
>> since the default indexing scheme has been changed).
>>
>> Kingsley
>>     
>>> Best
>>> Hugh
>>>
>>>
>>> On 28/07/2009 11:17, "Kingsley Idehen" <kidehen@openlinksw.com> wrote:
>>>
>>> Hugh Glaser wrote:
>>>  
>>>       
>>>> For the record (  Alan!).
>>>> I consider it bad practice to keep the knowledge about linking in the same
>>>> KB as the substantive knowledge you are representing.
>>>> You need two KBs: one for the knowledge you are publishing, and one for the
>>>> linkage you are working on.
>>>> These have very different provenance, maintenance patterns, etc..
>>>> And you can include a link from URIs that you generate to the linkage KB.
>>>>
>>>>    
>>>>         
>>> For terminology consolidation purposes, what you call a  KB is  a
>>> "Linked Data Space" in my parlance :-)
>>>
>>> Yes, the partitioning suggested above is very important. Thus, you need
>>> purpose specific Linked Data Spaces  (hosing many Named Graphs) if you
>>> seek to make things a little clearer to data consumers and their agents.
>>>  
>>>       
>>>> In fact, this would then help Alan's problem about sameAs:- he could simply
>>>> decide not to get your view of the linkage, whereas with sameAs in the
>>>> resources he has no choice but to accept your view, and even your predicate
>>>> when he resolves a URI or queries the SPARQL.
>>>>
>>>> And I do agree with you about minting URIs to your local stuff, including
>>>> authors; it is error-prone to try to re-use things like dbpedia for this, on
>>>> any scale. And this is why you need to tackle the linkage problem as a
>>>> separate engineering activity.
>>>>
>>>> Best
>>>> Hugh
>>>>
>>>> (Of course I do have some software and architecture that supports separate
>>>> linkage KBs (our CRS) so I would say this, but nevertheless I think it is
>>>> the correct engineering approach, however it is done. Separation of
>>>> Concerns.)
>>>>
>>>>    
>>>>         
>>> Note, we've partitioned DBpedia in such a way that you now have a Graph
>>> IRI for each data set within this particular Linked Data Space.
>>>
>>> Kingsley
>>>  
>>>       
>>>> On 28/07/2009 02:23, "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...
>>>>>
>>>>>      
>>>>>           
>>>> 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
>>>>    2. Mint URIs pointing to representations of authors of local etexts
>>>>
>>>>    3. In resources of etexts, include owl:sameAs links to DBpedia
>>>> resources
>>>>    4. In resources of etexts, point to local URIs of authors
>>>>
>>>>    5. In resources of authors, include owl:sameAs links to DBpedia
>>>> resources
>>>>    6. In resources of authors, include owl:creatorOf links to local
>>>> etexts
>>>>
>>>>    7. For extra credit, do the same thing for subjects/keywords
>>>>
>>>> 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#">
>>>>    <rdf:Description
>>>>      rdf:about="http://infomotions.com/etexts/id/more-utopia-221"
>>>>      owl:sameAs="http://dbpedia.org/resource/Utopia_(book)">
>>>>      <dcterms:title>Utopia</dcterms:title>
>>>>      <dcterms:creator
>>>> rdf:resource="http://infomotions.com/etexts/authors/resource/thomas-more
>>>> " />
>>>>    </rdf:Description>
>>>> </rdf:RDF>
>>>>
>>>>
>>>> <!-- 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>
>>>>
>>>>
>>>> <!-- 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>
>>>>
>>>> --
>>>> Eric Lease Morgan
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>    
>>>>         
>>> --
>>>
>>>
>>> Regards,
>>>
>>> Kingsley Idehen       Weblog: http://www.openlinksw.com/blog/~kidehen
>>> President & CEO
>>> OpenLink Software     Web: http://www.openlinksw.com
>>>
>>>
>>>
>>>
>>>
>>>
>>>  
>>>       
>> --
>>
>>
>> Regards,
>>
>> Kingsley Idehen       Weblog: http://www.openlinksw.com/blog/~kidehen
>> President & CEO
>> OpenLink Software     Web: http://www.openlinksw.com
>>
>>
>>
>>
>>
>>     
>
>
>   


-- 


Regards,

Kingsley Idehen	      Weblog: http://www.openlinksw.com/blog/~kidehen
President & CEO 
OpenLink Software     Web: http://www.openlinksw.com
Received on Wednesday, 29 July 2009 11:36:49 UTC

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