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Re: How do you flag a resource which is not available anymore?

From: Bernard Vatant <bernard.vatant@mondeca.com>
Date: Mon, 2 Jun 2014 10:17:23 +0200
Message-ID: <CAK4ZFVH-i-pFjv4TTGthE22ZmSx2yELLwX+FoVqon0mEuxX5VQ@mail.gmail.com>
To: Simon Spero <sesuncedu@gmail.com>
Cc: "public-vocabs@w3.org" <public-vocabs@w3.org>
Simon

Thanks for the reference, not yet looked into it in details, but as
answered to Ed, we're not looking for an overkill solution :)


2014-05-30 23:13 GMT+02:00 Simon Spero <sesuncedu@gmail.com>:

> This paper is generally relevant to the semantics, though it doesn't solve
> the specific problem:
>
> Representing and Querying Validity Time in RDF and OWL: A Logic-Based
> Approach✩
> Boris Motik, Oxford University Computing Laboratory, Oxford, UK
>
>  http://www.cs.ox.ac.uk/boris.motik/pubs/m12validity-time.pdf
>
> PROV-O can handle the use case, but has the downside of being PROV-O, and
> requiring a few blank nodes (validity is a bit fuzzy).
>
> http://www.w3.org/TR/2013/REC-prov-o-20130430/#invalidatedAtTime
> http://www.w3.org/TR/2013/REC-prov-o-20130430/#Revision
>
> Also, note that the ontology named by a version IRI is fixed;  if the IRI
> becomes impossible to dereference, the cached content should always be
> valid;  however, this may not be the case if the base IRI is used.
>

Indeed! But the use of versionIRI in LOV vocabularies is not a general
practice, far from it : See http://bit.ly/1nH1vlq
Less than 10% of vocabularies have a owl:versionIRI declaration, and those
who use it don't always do it correctly :(
More generally the versioning policy is globally a mess ... See
http://bit.ly/RWoZUu
Very often there is no version number or date whatsoever, or they are not
consistent between the documentation and RDF files (you can have one date
in the html, another in the RDF/XML file, and yet another one in the Turtle
...


> The contents of the LOV-back-machine is as valid as it ever was.
>  It is possible that an unversioned ontology  might have changed between
> the last capture and the 404
>

This should not happen if the LOV-Bot, which is tracking changes on a daily
basis, does its job properly. But due to content negotiation issues and
dozens of other reasons, it is not always the case. And very small changes
like corrections of typos can induce the LOV-Bot into uploading of a new
version, althogh the formal version information has not changed.

But those are known issues that I would not want to blur the simple
question at hand : simply providing the information that this URI used to
be dereferenceable, but is currently no more, so if you use this vocabulary
in your data, the semantics will not be found through the vocabulary URI,
but through some version backup etc. We are in terra incognita there ...

Bernard


>
> On Fri, May 30, 2014 at 5:09 AM, Bernard Vatant <
> bernard.vatant@mondeca.com> wrote:
>
>> Hi vocabulers
>>
>> We have more and more records in LOV of which URIs are 404,
>> unfortunately, with no replacing resource whatsoever.
>> See e.g., http://lov.okfn.org/dataset/lov/details/vocabulary_dir.html etc
>> We want to keep the record in LOV, along with backup versions, such as
>>
>> http://lov.okfn.org/dataset/lov/agg/archives/dir_dir/file_dir_2006-06-27.n3
>>
>> We want to flag the URI some way, such as some "offlineSince" or
>> "validUntil" property, with value a xsd:date. This property would be added
>> to the VOAF vocabulary, unless someone knows about an existing property to
>> express that. There are various "valid" properties in DC terms and other
>> vocabularies, but not sure they capture the expected semantics.
>>
>> Thanks for any suggestion.
>>
>> --
>>
>> *Bernard Vatant *
>> Vocabularies & Data Engineering
>> Tel :  + 33 (0)9 71 48 84 59
>> Skype : bernard.vatant
>> http://google.com/+BernardVatant
>> --------------------------------------------------------
>> *Mondeca*
>> 35 boulevard de Strasbourg 75010 Paris
>> www.mondeca.com
>> Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
>> ----------------------------------------------------------
>>
>
>


-- 

*Bernard Vatant*
Vocabularies & Data Engineering
Tel :  + 33 (0)9 71 48 84 59
Skype : bernard.vatant
http://google.com/+BernardVatant
--------------------------------------------------------
*Mondeca*
35 boulevard de Strasbourg 75010 Paris
www.mondeca.com
Follow us on Twitter : @mondecanews <http://twitter.com/#%21/mondecanews>
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Received on Monday, 2 June 2014 08:18:11 UTC

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