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Re: The Ordered List Ontology

From: Harry Halpin <hhalpin@ibiblio.org>
Date: Thu, 1 Jul 2010 00:24:02 +0100
Message-ID: <AANLkTimhBcsbUs4l29jHuNVsCuQib8FRSbKVurC7rwaB@mail.gmail.com>
To: Pat Hayes <phayes@ihmc.us>
Cc: Dan Brickley <danbri@danbri.org>, Toby Inkster <tai@g5n.co.uk>, Graham Klyne <GK@ninebynine.net>, Bob Ferris <zazi@elbklang.net>, Linked Data community <public-lod@w3.org>, Semantic Web <semantic-web@w3.org>
On Wed, Jun 30, 2010 at 8:17 PM, Pat Hayes <phayes@ihmc.us> wrote:
>
> On Jun 30, 2010, at 1:15 PM, Dan Brickley wrote:
>
>> On Wed, Jun 30, 2010 at 6:34 PM, Pat Hayes <phayes@ihmc.us> wrote:
>>>
>>> On Jun 30, 2010, at 6:45 AM, Toby Inkster wrote:
>>>
>>>> On Wed, 30 Jun 2010 10:54:20 +0100
>>>> Dan Brickley <danbri@danbri.org> wrote:
>>>>
>>>>> That said, i'm sure sameAs and differentIndividual (or however it is
>>>>> called) claims could probably make a mess, if added or removed...
>>>>
>>>> You can create some pretty awesome messes even without OWL:
>>>>
>>>>       # An rdf:List that loops around...
>>>>
>>>>       <#mylist> a rdf:List ;
>>>>               rdf:first <#Alice> ;
>>>>               rdf:next <#mylist> .
>>>>
>>>>       # A looping, branching mess...
>>>>
>>>>       <#anotherlist> a rdf:List ;
>>>>               rdf:first <#anotherlist> ;
>>>>               rdf:next <#anotherlist> .
>>>>
>>>
>>> They might be messy, but they are *possible* structures using pointers,
>>> which is what the RDF vocabulary describes.  Its just about impossible to
>>> guarantee that messes can't happen when all you are doing is describing
>>> structures in an open-world setting. But I think the cure is to stop
>>> thinking that possible-messes are a problem to be solved. So, there is
>>> dung
>>> in the road. Walk round it.
>>
>> Yes.
>>
>> So this is a point that probably needs careful presentation to new
>> users of this technology. Educating people that they shouldn't believe
>> any random RDF they find in the Web, ... now that is pretty easy.
>> Still needs doing, but it shadows real world intuitions pretty well.
>>
>> If in real life you think the Daily Mail is full of nonsense, then it
>> isn't a huge leap to treat RDFized representations of their claims
>> with similar skepticism (eg. see
>> http://data.totl.net/cancer_causes.rdf for a great list of Things The
>> Daily Mail Say Might Cause Cancer).
>>
>> *However* it is going to be tough to persuade developers to treat a
>> basic data structure like List in the same way.
>
> Sure.  But what they need to grok is that RDF does not have ANY data
> structures in it (except maybe triples). It describes data structures, just
> like it describes everything else. It does not PROVIDE data structures.
> Maybe it should - make the case! - but then it will need to change rather
> drastically in its very foundation. Triples describing lists are not the
> same as triples-plus-lists.

The issue is here that RDF started as a metadata format to "describe"
data I believe, and at this point with the Linked Data is now being
transformed into a generic language *for* data, period.  The lack of
lists (and hashes, and other things programmers are used to dealing
with) in a reasonable (read "non-XML") syntax is one of the primary
reasons the developer community has moved towards JSON.

Now, the question is "Would it be possible to provide a JSON-like
number of data-structures in RDF, and what would this do to its
semantics?" Pat?

Given that programming langauge semantics define these things all the
time and it's pretty standard, I imagine its possible. But it might
make life hard for the principles that RDF was founded upon, i.e. the
sort of "open world" flavor of it all.

Thus, I imagine it's a trade-off, like most good things in life :)

>
> Pat
>
>> Lists are the kinds of
>> thing we expect to be communicated perfectly or to get some low-level
>> error. A lot of developers will write RDF-consuming code that won't
>> anticipate errors. Hopefully supporting software libraries can take
>> some of the strain here...
>>
>> cheers,
>>
>> Dan
>>
>>
>
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Received on Wednesday, 30 June 2010 23:24:32 GMT

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