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Re: An IRC discussion with Alexandre Bertails re SSUE-19:

From: Alexandre Bertails <bertails@w3.org>
Date: Thu, 06 Jun 2013 13:56:21 -0400
Message-ID: <51B0CD45.4090408@w3.org>
To: Henry Story <henry.story@bblfish.net>
CC: Roger Menday <roger.menday@uk.fujitsu.com>, Pierre-Antoine Champin <pierre-antoine.champin@liris.cnrs.fr>, Linked Data Platform Working Group <public-ldp-wg@w3.org>
On 06/06/2013 11:19 AM, Henry Story wrote:
>
> On 6 Jun 2013, at 16:06, Alexandre Bertails <bertails@w3.org> wrote:
>
>>>>>
>>>>>
>>>>> Well, when you find the following HTML
>>>>>
>>>>>   <form action="foo" method="foo">
>>>>>
>>>>> at <bar>, do you believe it? Do you try and perform a POST on <foo>?
>>>>> I guess the answer is the same: if you trust the source, then yes,
>>>>> you're allowed to start interacting with <bar> as if it were an LDPC.
>>>
>>> When a form is submitted, the processor (indicated by the 'action'
>>> parameter) is doing something pretty similar to a LDPC. I suppose the
>>> HTML equivalent of issue-73, would be "list all of requests that have
>>> been processed". For me, this isn't very interesting because the
>>> information I need is in the documents I am browsing.
>>
>> The semantics of <form> is defined in HTML, which tells the web
>> browser what to do with it. I don't have any problem with that.
>
> Good. So take the RDF semantics document http://www.w3.org/TR/rdf-mt/
> which defines the semantics of RDF syntaxes.
>
> It defines truth as
>
> ~~~~~~~~~~~~~~~~~~~~~
> if E is a ground triple s p o. then I(E) = true if
>
> s, p and o are in V, I(p) is in IP and <I(s),I(o)> is in IEXT(I(p))
>
> otherwise I(E)= false.
> ~~~~~~~~~~~~~~~~~~~~~
>
> So this is
>
> I ({ <log> a ldp:Container }) = true
>
> if <log>, rdf:type and ldp:Container are in V ( they are once transformed into absolute URLs )
> I(rdf:type) is in IP - it is a property, so yes.
> <I(<log>, I(ldp:Container> is in IEXT(I(rdf:type)) - well that depends on the the definition
> of ldp:Container which is defined by the LDP spec
> as explained by the definition of the ldp namespace document:

I have to say that I don't understand that part. How do you fix the
interpretation of ldp:Container to be its definition in the document
that you dereference at http://www.w3.org/ns/ldp? Isn't it introducing
something that is not defined in RDF? I thought that RDF was not
relying on HTTP on purpose.

>
> ~~~~~~~~~~~~~~~~~~~~~
> $ curl -H "Accept: text/turtle" http://www.w3.org/ns/ldp
> ...
>
> ldp:Container     a :Class;
>           :comment """A Linked Data Platform Resource (LDPR) that also conforms to
>      additional patterns and conventions for managing membership.
>      Readers should refer to the specification defining this ontology for the list of
>      behaviors associated with it.""";
>           :isDefinedBy ldp:;
>           :label "Container";
>           :subClassOf ldp:Resource;
>           vs:term_status "unstable" .
> ...
> ~~~~~~~~~~~~~~~~~~~~~~~~
>
> and so the question is whether <log> indeed fulfills the restrictions defined
> by LDP. It could be that the definition of the LDP spec is not complete enough to
> make any intelligent distinction.... That is where the question should be.

Of course, that works assuming that the interpretation is related to
what you dereference (btw, RDF does not tell you how to find
#Container in http://www.w3.org/ns/ldp).

But let's pretend that it works, just for a moment, and let's go back
to the questions that you erased and didn't answer:

* how do I know that <foo> is an LDPR?
-> there is no rdf:type defined for it, and I'm pretty sure that we
    don't want one

* how do I know that <foo> is neither an LDPC nor an LDPR?
-> it's hard to say because of the open world assumption, unless you
    close that world, eg. the document at <foo>

* how do I know that I can interact with <foo> using the SPARQL Graph 
Protocol?
-> yeah, how do I know that by the way?

* if I find out that <foo> a ldp:Container while looking at <bar>,
   should I consider this information as authoritative?
-> as we're assuming that your explanation works, consider that you
    have answered this one already

Also:

* if I agree that "any resource that yields a Turtle representation
   becomes de facto an LDPR (even if read-only)" (quoting
   Pierre-Antoine Champin), then with the same reasoning, should I
   consider <foo> as a named graph as well, according to the SPARQL
   Graph Protocol?
-> then I hope that they will never define contradictory interactions

Alexandre.

>
>
> Henry
>
>
>
> Social Web Architect
> http://bblfish.net/
>
>
Received on Thursday, 6 June 2013 17:56:40 UTC

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