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Re: Do the following examples generate any triples?

From: Mark Birbeck <mark.birbeck@formsPlayer.com>
Date: Wed, 9 Jan 2008 10:18:42 +0000
Message-ID: <a707f8300801090218t1e7b84e1r1bd6b504e05e65c3@mail.gmail.com>
To: "Manu Sporny" <msporny@digitalbazaar.com>
Cc: RDFa <public-rdf-in-xhtml-tf@w3.org>

Hi Manu,

> Just to understand when certain triples are generated, it is my
> understanding that all of the examples below should not generate any
> triples, please verify:

Thanks (again!) for taking the trouble to lay the issues out clearly.
I delayed replying last night, because I wanted to see other input
first.

To answer the question in your subject line, yes they all generate triples.


> -----------------------------------------------------------------
> <div resource="#me" rel="foaf:knows">
>    <span resource="#ben">
> </div>
> -----------------------------------------------------------------

In all models (except Ivan's new one...see latest email), the first
line generates a triple as normal:

  <> foaf:knows <#me> .

and the second line does nothing.

The rule is essentially that in the presence of @rel, @resource is an
object for that element. (It may also be a subject for nested
elements, but that is separate.)


> -----------------------------------------------------------------
> <div href="#me" rel="foaf:knows">
>    <span href="#ben">
> </div>
> -----------------------------------------------------------------

As above, the first line is as it has always been:

  <> foaf:knows <#me> .

The rule is essentially that in the presence of @rel, @href is an
object for that element. (Once again, it may play the role of a
subject for any nested statements, but that is separate.)


> -----------------------------------------------------------------
> <div href="#me">
>    <span rel="foaf:knows" href="#ben">
> </div>
> -----------------------------------------------------------------

Right...this concerns the first half of my 'two-part' argument; I
believe that this should generate the following:

  <#me> foaf:knows <#ben> .

The rationale is that if the first @href had @about and @rel on it:

  <div about="#manu" rel="foaf:knows" href="#me">
    <span rel="foaf:knows" href="#ben">
  </div>

then no-one would mind that the @href on the first line should set the
subject for subsequent statements, as follows:

  <#manu> foaf:knows <#me> .
  <#me> foaf:knows <#ben> .

In other words, @href is able to set a subject -- even if it is also
an object -- depending on what comes next in the chaining. So if it
can play this role _with_ @about and @rel on the same element, it
seems to be consistent that it should be able to play this role
_without_ @about and @rel on the same element.

Ben now seems to be agreeing with this in his reply to you, but I'll
comment more on that in a response to his response.

So to return to your example:

  <div href="#me">
    <span rel="foaf:knows" href="#ben">
  </div>

the rule is essentially that in the absence of @rel, _any_ RDFa
resource attribute can be a subject, assuming of course that there are
further statements to be a subject of:

  <div resource="#A">
    <span rel="a:b" href="#B">
  </div>

  <div href="#A">
    <span rel="a:b" href="#B">
  </div>

  <div about="#A">
    <span rel="a:b" href="#B">
  </div>

  <img src="A.jpg">
    <span rel="a:b" href="#B">
  </img>


> -----------------------------------------------------------------
> <div resource="#me" rel="foaf:knows">
>    <div resource="#ben">
>       <a rel="foaf:knows" href="#mark">Mark</a>
>    </div>
> </div>
> -----------------------------------------------------------------

The first line is, as it always was:

  <> foaf:knows <#me> .

The second line does nothing in relation to the first line, but
according to our previous rule it sets the subject for any contained
statements:

  <#ben> foaf:knows <#mark> .

As I said, Ben seems to agree with this now, so thanks to your efforts
we have narrowed the problem down quite a lot. I'll spell out the
detail in my response to Ben.

Regards,

Mark

-- 
  Mark Birbeck, formsPlayer

  mark.birbeck@formsPlayer.com | +44 (0) 20 7689 9232
  http://www.formsPlayer.com | http://internet-apps.blogspot.com

  standards. innovation.
Received on Wednesday, 9 January 2008 10:18:48 GMT

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