Re: [ISSUE-57] Drawback to Parallel Properties

Thank you both for the links to more recent information. There appears
to be a slight error on p.481 of the WebSci '13 paper:

"Tennison [4] groups *real* and *immediate* under the name 'direct' on
the basis of a similar analysis."

The URIs in Data Primer of 07 March 2013 seems rather to call only
immediate properties "direct"; real properties are called "implied"
(Section 4). The link to the primer in /TR/ is also broken (404),
though it is available in /2001/tag/.

For anyone following this thread, there is a near perfect duplicate of
the WebSci '13 paper available on ht's website, though it is missing
page numbers:

http://www.ltg.ed.ac.uk/~ht/WebSci2013/websci.pdf

Possibly more comments to come as I digest this material.

On Thu, Oct 30, 2014 at 2:13 PM, Jonathan A Rees <rees@mumble.net> wrote:
> Hi Sean,
>
> You are absolutely right, and I don't think it's such a minor comment.
> Should the 'Providing and Discovering' or 'URIs in data' documents ever be
> revised, the point should be made.
>
> The reasoning vulnerability may be related to the fact that (as far as I've
> heard) the 'URIs in data' proposal has not had much uptake.
>
> Parallel properties was seen as a compromise intended to get
> interoperability between the two popular behavior patterns. Like many
> compromises, it may end up failing to please anyone.
>
> Parallel properties certainly was on offer (via 'URIs in data') as an
> opportunity to do away with the much maligned 303 and 2NN business. TimBL
> and Eric Prud'hommeaux turned down the offer, as seen by their recent effort
> to push 2NN through the IETF process. Perhaps the rejection was for reasons
> similar to what you describe - it's hard to reason correctly about parallel
> properties.
>
> A consistency checker (e.g. an OWL reasoner) could detect the problems you
> raise, given the right axioms. However, most RDF sources are not too keen on
> consistency validation and would happily generate noninteroperable content
> even if there were a published specification. We've seen this situation
> before, where HTTP servers, with which validation has never been popular,
> happily generate noninteroperable HTTP content.
>
> I wonder if this old interoperability discussion is completely over, or if
> it's a time bomb that won't be taken seriously until the pain level gets
> high enough (the RDF analog of 'browser wars'). Who knows whether that will
> ever happen.
>
> Best
> Jonathan
>
>
> On Wed, Oct 29, 2014 at 10:26 AM, Sean B. Palmer <sean@miscoranda.com>
> wrote:
>>
>> This is a minor comment on a technique described in:
>>
>> Providing and Discovering URI Documentation
>> Editor's Draft 2 February 2012
>> http://www.w3.org/2001/tag/awwsw/issue57/20120202/
>>
>> Section 4.2 describes a method called parallel properties, which has
>> been independently invented on several occasions.
>>
>> The method consists of creating properties that are designed to refer
>> to the "designated subject" of a document, which bears some relation
>> and may even be equivalent to its foaf:primaryTopic.
>>
>> To expand such references, we also need to give a name to the
>> relationship between the asserted property and the inferred property.
>> In the example graph given in the section, these are eq:epicenter and
>> "has epicenter". I shall refer to this relation as the "direct
>> property".
>>
>> That is to say, this example from the section:
>>
>>   <http://example/eq018> eq:magnitude 6.9.
>>   <http://example/eq018> eq:epicenter <geo:37.040,-121.877>.
>>
>> Implies the following:
>>
>>   <http://example/eq018> pp:designatedSubject [
>>     [ is pp:directProperty of eq:magnitude ] 6.9;
>>     [ is pp:directProperty of eq:epicenter ] <geo:37.040,-121.877>
>>   ].
>>
>> There is a significant drawback to this method. It is that it appears
>> that you can use non-parallel properties on the same subject, whereas
>> in fact this leads to inconsistencies. A good example of a common
>> non-parallel property that someone may attempt to use is owl:sameAs:
>>
>>   <http://example/eq018> owl:sameAs
>>     <http://example2/document.rdf#eq018> .
>>
>> This statement would cause all sorts of inferential chaos. In the
>> earthquake example such incorrect inferences may not be regarded as
>> especially harmful, but there are alternative scenarios in which they
>> would be, such as where a document has another document as its
>> designated subject. In that case, the inferential chaos caused by
>> owl:sameAs would make the metadata of both documents
>> indistinguishable.
>>
>> To recap, the properties eq:magnitude and eq:epicenter in the example
>> appear to have the nature of non-parallel properties, and would cause
>> confusion unless specifically documented as a pp:ParallelProperty
>> instances, with the characteristics of parallel properties being
>> widely known. This problem is similar to spoofing. There is no
>> requirement preventing it in the list of desiderata (Section 1.1).
>>
>> Note that parallel property analogues to non-parallel properties can
>> be made. In the case of owl:sameAs, for example, we could say:
>>
>>   { ?s pp:designatedSubjectSameAs ?o } =>
>>     { ?s pp:designatedSubject [ owl:sameAs ?o ] } .
>>
>> And also:
>>
>>   { ?s pp:sameDesignatedSubjectAs ?o } =>
>>     { ?s pp:designatedSubject
>>         [ owl:sameAs [ is pp:designatedSubject of ?o ] ] }.
>>
>> But this approach is not very straightforward.
>>
>> --
>> Sean B. Palmer, http://inamidst.com/sbp/
>>
>



-- 
Sean B. Palmer, http://inamidst.com/sbp/

Received on Thursday, 30 October 2014 15:16:24 UTC