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Re: Is it best practices to use a rdfs:seeAlso link to a potentially multimegabyte PDF?, existing predicate for linking to PDF?

From: Christopher Gutteridge <cjg@ecs.soton.ac.uk>
Date: Thu, 13 Jan 2011 10:23:13 +0000
Message-ID: <EMEW3|780ca9786990661a573849e08c79a63cn0CANI03cjg|ecs.soton.ac.uk|4D2ED291.8090303@ecs.soton.ac.uk>
To: Martin Hepp <martin.hepp@ebusiness-unibw.org>
CC: nathan@webr3.org, Tim Berners-Lee <timbl@w3.org>, Vasiliy Faronov <vfaronov@gmail.com>, Toby Inkster <tai@g5n.co.uk>, Peter DeVries <pete.devries@gmail.com>, public-lod@w3.org
One obvious solution is to use an extra triple to indicate that the URL 
is a serialisation of some triples. eg.

  <rdf:Description rdf:about="...URI-X...">
    <rdfs:label>the name of the thing for which more data is 
available</rdfs:label>
    <rdfs:seeAlso>
      <rdf:Description rdf:about="...RDF-URL...">
        <rdf:type 
rdf:resource="http://purl.org/xtypes/Document-RDFSerialisation" />
      </rdf:Description>
    </rdfs:seeAlso>
  </rdf:Description>
 

Martin Hepp wrote:
> Hi Nathan:
>
>> There are other ways of looking at this, remembering we're in the 
>> realm of machine readable information and the context of RDF. 
>> rdfs:seeAlso is used to indicate a resource O which may provide 
>> additional information about the resource S - information in this 
>> context being rdf, information for the machine - so we can say that 
>> if O points to a resource that doesn't contain any information at all 
>> (no rdf, or isn't the subject of any statements) then we've created a 
>> meaningless statement, it may as well be { S rdfs:seeAlso [] }
>>
>> One could easily suggest that it's good for RDF Schema properties to 
>> have some use in RDF, and thus that if rdfs:seeAlso is used in a 
>> statement, that it should point to some "information", some rdf for 
>> the machine, otherwise it's a bit of a pointless property.
>>
>> Given the above, we could take the meaning of the sentence "no 
>> constraints are placed on the format of those representations" and 
>> assert that this simply means that RDF/XML is not required, and that 
>> any RDF format can be used.
>
> I don't buy in to restricting the meaning of "data" in the context of 
> RDF to "RDF data". If the subject or object of RDF triples can be any 
> Web resource (information and non-information resource), then the 
> range of rdfs:seeAlso should also include information resources (i.e., 
> data) of a variety of conceptual and syntactic forms.
>
> And PDF, HTML without RDFa as well as images clearly qualify as data. 
> They are also clearly machine-accessible. If you are still not 
> convinced: What about CSV files or text files containing ACE 
> (controlled English), or OData / GData?
>
> By the way, the problem of having to load huge amounts of data 
> following rdfs:seeAlso is not limited to PDFs - even obeying Tim's 
> proposal means there could be huge RDF graphs linked to via 
> rdfs:seeAlso, and that is of course conceptually perfectly okay.
>
> After all, rdfs:seeAlso is not 
> rdfs:linkToASmallChunkOfVeryRelatedDateInRDF ;-) Data management and 
> data quality heuristics should not be solved at the conceptual level. 
> If old clients employ outdated heuristics, those clients should update 
> their heuristics, IMO.
>
> Best
> Martin
>
>
> On 12.01.2011, at 16:13, Nathan wrote:
>
>> Hi Martin,
>>
>> Martin Hepp wrote:
>>> For my taste, using rdfs:seeAlso is perfectly valid (yet suboptimal, 
>>> because too unspecific), according to the RDFS spec:
>>> http://www.w3.org/TR/rdf-schema/#ch_seealso
>>> Quote: "rdfs:seeAlso is an instance of rdf:Property that is used to 
>>> indicate a resource that might provide    additional information 
>>> about the subject resource.
>>> A triple of the form:
>>> S rdfs:seeAlso O
>>> states that the resource O may provide additional information about 
>>> S. It may be possible to retrieve representations of O from the Web, 
>>> but this is not required. When such representations may be 
>>> retrieved, ***no constraints are placed on the format of those 
>>> representations***."
>>
>>
>>
>> Generally it appears to me that rdfs:seeAlso is a property for a 
>> machine to follow in order to get more information, and that much of 
>> the usage mentioned in this thread requires a property which informs 
>> a human that they may want to check resource O for more information - 
>> essentially something similar to a hyperlink in a html document with 
>> no @rel value.
>>
>> Best,
>>
>> Nathan
>>
>
>

-- 
Christopher Gutteridge -- http://id.ecs.soton.ac.uk/person/1248

You should read the ECS Web Team blog: http://blogs.ecs.soton.ac.uk/webteam/
Received on Thursday, 13 January 2011 10:24:12 UTC

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