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meeting record: 2006-10-23 RDF-in-XHTML TF telecon

From: Ralph R. Swick <swick@w3.org>
Date: Mon, 23 Oct 2006 15:11:47 -0400
Message-Id: <5.1.0.14.2.20061023150923.038d7000@127.0.0.1>
To: public-rdf-in-xhtml-tf@w3.org
Cc: public-swd-wg@w3.org

The [1]record of today's RDF in XHTML telecon is ready for review.
A full text snapshot follows below.

  [1] http://www.w3.org/2006/10/23-htmltf-minutes.html

Topics
   1.  Action Item Review
   2. Reification

Summary of Action Items

[NEW] ACTION: Elias to send by email examples of HTML markup that could be problematic with reification [recorded in http://www.w3.org/2006/10/23-htmltf-minutes.html#action09]

[NEW] ACTION: Mark produce more examples of applicability of n-ary relations from IPTC documents [recorded in http://www.w3.org/2006/10/23-htmltf-minutes.html#action08]

[PENDING] ACTION: Ben start separate mail threads on remaining discussion topics [recorded in http://www.w3.org/2006/09/19-htmltf-minutes.html#action07]

[PENDING] ACTION: Ben update the issues list [recorded in http://www.w3.org/2006/09/19-htmltf-minutes.html#action08]

[PENDING] ACTION: Elias start an FAQ [recorded in http://www.w3.org/2006/10/03-htmltf-minutes.html#action10]

[PENDING] ACTION: Mark write examples/tests of striping support [recorded in http://www.w3.org/2006/10/16-htmltf-minutes.html#action10]

[PENDING] ACTION: Steven to put together sample XHTML2 doc with all mime type, etc.. [recorded in http://www.w3.org/2006/09/19-htmltf-minutes.html#action01]

[DONE] ACTION: Ben announce new URIs for editors' drafts to TF [recorded in http://www.w3.org/2006/10/16-htmltf-minutes.html#action04]

[DONE] ACTION: Elias summarize the reification discussion [recorded in http://www.w3.org/2006/10/16-htmltf-minutes.html#action11]

-Ralph

----

                            RDFa Task Force

23 Oct 2006

   [2]Agenda

      [2] http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2006Oct/0058.html

   See also: [3]IRC log, previous [4]2006-10-16

      [3] http://www.w3.org/2006/10/23-htmltf-irc
      [4] http://lists.w3.org/Archives/Public/public-rdf-in-xhtml-tf/2006Oct/0047.html

Attendees

   Present
          Ralph Swick, Ben Adida, Steven Pemberton, Mark Birbeck, Elias
          Torres

   Regrets
   Chair
          Ben

   Scribe
          Ralph

Contents

     * Topics
         1. Action Item Review
         2. Reification
     * Summary of Action Items
     _________________________________________________________

Action Item Review

   ACTION: [DONE] Ben announce new URIs for editors' drafts to TF
   [recorded in
   [9]http://www.w3.org/2006/10/16-htmltf-minutes.html#action04]

      [9] http://www.w3.org/2006/10/16-htmltf-minutes.html#action04

   ACTION: [DONE] Elias summarize the reification discussion [recorded
   in [10]http://www.w3.org/2006/10/16-htmltf-minutes.html#action11]

     [10] http://www.w3.org/2006/10/16-htmltf-minutes.html#action11

   ACTION: Mark write examples/tests of striping support [recorded in
   [11]http://www.w3.org/2006/10/16-htmltf-minutes.html#action10]
   [CONTINUES]

     [11] http://www.w3.org/2006/10/16-htmltf-minutes.html#action10

   Mark: examples is nearly ready to send out

   ACTION: Ben update the issues list [recorded in
   [12]http://www.w3.org/2006/09/19-htmltf-minutes.html#action08]
   [CONTINUES]

     [12] http://www.w3.org/2006/09/19-htmltf-minutes.html#action08

   ACTION: Ben start separate mail threads on remaining discussion
   topics [recorded in
   [13]http://www.w3.org/2006/09/19-htmltf-minutes.html#action07]
   [CONTINUES]

     [13] http://www.w3.org/2006/09/19-htmltf-minutes.html#action07

   ACTION: Steven to put together sample XHTML2 doc with all mime type,
   etc.. [recorded in
   [14]http://www.w3.org/2006/09/19-htmltf-minutes.html#action01]
   [CONTINUES]

     [14] http://www.w3.org/2006/09/19-htmltf-minutes.html#action01

   Steven: I work a bit on this each week; you can see changes

   <Steven> [15]http://www.w3.org/MarkUp/2006/xhtml2.xml

     [15] http://www.w3.org/MarkUp/2006/xhtml2.xml

   Steven: at the moment it is intentionally served as text/xml
   ... I will make a [16]snapshot as .xhtml so it is served with the
   correct MIME type

     [16] http://www.w3.org/MarkUp/2006/xhtml2.xhtml

   ... Also, we've submitted a WWW2007 RDFa workshop proposal

   Ben: reminder; we've targetted 27 Oct as date for code and examples
   of new syntax

   ACTION: Elias start an FAQ [recorded in
   [17]http://www.w3.org/2006/10/03-htmltf-minutes.html#action10] IN
   PROGRESS]

     [17] http://www.w3.org/2006/10/03-htmltf-minutes.html#action10

   Elias: just started it

   <EliasT> ... [18]http://esw.w3.org/topic/RDFa#FAQ

     [18] http://esw.w3.org/topic/RDFa#FAQ

Reification

   Mark: my impression after the discussion was that some of the
   problems were due to reification in a particular context
   ... for what RDFa needs, the issue seems more clear
   ... e.g. 'who said X' does seem to be clear
   ... in the references that Elias cited
   ... Dan's point is that he wants RDFa to be no more expressive than
   RDF/XML
   ... so that all RDFa can be transformed to RDF/XML

   Elias: I don't agree that it is clear how we can identify a triple

   Mark: if it's not clear how to do this in RDF/XML then we don't need
   to do it in RDFa

   Elias: by 'identify' I mean know whether it exists in a specific
   named graph
   ... it's not clear how to say 'that triple'
   ... the RDF spec is clear that reification is about identification,
   not about quoting
   ... but we don't have a clear way to identify

   Mark: but if RDF/XML hasn't solved the problem then RDFa can't solve
   it either

   Elias: but we have documents

   Mark: we can name some other type of Statement but we can't name an
   RDF triple
   ... if we wanted to, we could say there is an xyz:Statement that has
   implicit information
   ... but we'd still need some magic if there's no way to say that
   this maps to an rdf:Statement

   Elias: RDF reification does not say that if you have the quad it
   implies the triple

   Mark: in terms of generation from RDF/XML that's the case
   ... you're not supposed to assume that the original triple exists
   ... but that doesn't prevent the other way around
   ... RDFa could say the triple exists

   Ben: we can start with some RDFa and specify what it means in
   RDF/XML

   <EliasT> Note that asserting the reification is not the same as
   asserting the original statement, and neither implies the other.
   That is, when someone says that John said something about the weight
   of a tent, they are not making a statement about the weight of a
   tent themselves, they are making a statement about something John
   said. Conversely, when someone describes the weight of a tent, they
   are not also making a statement about a statement they made (since
   they may

   ^[19]excerpt from RDF spec

     [19] http://www.w3.org/TR/rdf-primer/#reification

   Ben: but we can say that the dc:creator of the s/p/o quad is
   responsible for a triple asserted by that quad

   Elias: we want to attach provenance to HTML documents, not to graphs

   Ben: we know how to do that
   ... e.g. a LINK or a META on a DIV can say who is the creator of
   that DIV

   Mark: even without reification there is a question
   ... on the one hand you're making statements about the DIV
   ... on the other hand we're reusing it at a higher level to
   represent a bnode

   Ben: but the bnode is just a local concept

   Mark: to be consistent, the only thing you'd be making statements
   about is the DIV

   <EliasT> <div class="foo bar"/>

   Mark: similar issue to describing the car or the web page that
   describes the car

   Elias: given a div with two classes, can we say that the two type
   statements were made by different creators?

   Ralph: that seems a corner case

   Mark: when we embed metadata in the document rather than have it
   standalone then we lose the ability to attach provenance to the
   metadata

   Ben: we could add more to reify the class="foo bar" case if we
   really wanted to

   <EliasT> <div>

   <EliasT> <meta property="class">foo</meta>

   <EliasT> <meta property="class">bar</meta>

   <EliasT> </div>

   Ben: that would be one way to think about it but this is still more
   than RDF/XML gives
   ... but another way is to simply write the triple two times

   Mark: 2 choices; 1. use reification as it is
   ... we've agreed that you can't connect between the asserted triple
   and the quad
   ... 2. say that the "RDF-ness" is not really in the document;
   explode the document, expand every property in the document so that
   the contents are all objects, etc.
   ... then this exploded version is converted back 'down' to RDF/XML
   ... method 2 makes things quite complicated

   Elias: even if we go with method 1, there is still the question --
   adding provenance to a DIV adds statements to multiple triples
   ... and that DIV could become the object of some enclosing element

   <EliasT> <div rel="foo" rev="bar">

   <EliasT> .. reification ...

   <EliasT> </div>

   Elias: if our granularity is the XML element the reification applies
   to two different things

   Mark: I could just about live with this
   ... but in the IPTC case, given the statement "Reuters says this
   article is about skiing. Reuters is 80% confident in this
   categorization."
   ... and separately "BBC says this article is about skiing. BBC is
   60% confident in this categorization."

   Ben: but this is an RDF problem too

   Elias: if rev="bar" was added later by a different person than
   rel="foo" ...

   Ben: you're talking about multiple authors changing the same piece
   of HTML

   Elias: don't confuse two things; an HTML element and ...
   ... the HTML element can create many triples

   Ben: I can understand that attaching a link to a DIV is attaching
   the link to every triple
   ... this may not be the best practice, but that _is_ what the HTML
   says

   <EliasT> <link rel="iptc:category" href="[iptc:skiiing]">

   <EliasT> <meta property="iptc:confidence" content=".8" />

   <EliasT> </link>

   Elias: Reuter's 80% confidence is not in the statement itself but
   that the category is skiing
   ... if I add iptc:joke to the categories, the 80% should still only
   apply to skiing

   Ben: but why do we need to support that?

   Elias: I am also worried about the case where the LINK element
   participates in an enclosing rev property

   Ben: we need to look at some tricky examples give this new proposal
   and make sure they turn out sort-of reasonable

   Mark: now I'm having trouble seeing these examples as reification
   ... I am reevaluating my earlier comments suggesting that n-ary
   relations were not what we wanted
   ... the category/confidence example can be done with n-ary relatoins
   ... IPTC used a LINK element to add a confidence
   ... perhaps a way out of the provenance issue is to handle it at the
   HTML level
   ... use an additional HTML element rather than adding properties [to
   an existing one]
   ... I'm starting to see that an n-ary solution fits more cases than
   I'd originally thought
   ... I will extract more examples from original IPTC documents

   ACTION: Mark produce more examples of applicability of n-ary
   relations from IPTC documents [recorded in
   [20]http://www.w3.org/2006/10/23-htmltf-minutes.html#action08]

   ACTION: Elias to send by email examples of HTML markup that could be
   problematic with reification [recorded in
   [21]http://www.w3.org/2006/10/23-htmltf-minutes.html#action09]

   <EliasT> [22]http://www.w3.org/TR/swbp-n-aryRelations/#useCase1

     [22] http://www.w3.org/TR/swbp-n-aryRelations/#useCase1

   <Steven> [23]http://www.w3.org/People/Ivan/

     [23] http://www.w3.org/People/Ivan/

Summary of Action Items

   [NEW] ACTION: Elias to send by email examples of HTML markup that
   could be problematic with reification [recorded in
   [24]http://www.w3.org/2006/10/23-htmltf-minutes.html#action09]
   [NEW] ACTION: Mark produce more examples of applicability of n-ary
   relations from IPTC documents [recorded in
   [25]http://www.w3.org/2006/10/23-htmltf-minutes.html#action08]

   [PENDING] ACTION: Ben start separate mail threads on remaining
   discussion topics [recorded in
   [26]http://www.w3.org/2006/09/19-htmltf-minutes.html#action07]
   [PENDING] ACTION: Ben update the issues list [recorded in
   [27]http://www.w3.org/2006/09/19-htmltf-minutes.html#action08]
   [PENDING] ACTION: Elias start an FAQ [recorded in
   [28]http://www.w3.org/2006/10/03-htmltf-minutes.html#action10]
   [PENDING] ACTION: Mark write examples/tests of striping support
   [recorded in
   [29]http://www.w3.org/2006/10/16-htmltf-minutes.html#action10]
   [PENDING] ACTION: Steven to put together sample XHTML2 doc with all
   mime type, etc.. [recorded in
   [30]http://www.w3.org/2006/09/19-htmltf-minutes.html#action01]

     [26] http://www.w3.org/2006/09/19-htmltf-minutes.html#action07
     [27] http://www.w3.org/2006/09/19-htmltf-minutes.html#action08
     [28] http://www.w3.org/2006/10/03-htmltf-minutes.html#action10
     [29] http://www.w3.org/2006/10/16-htmltf-minutes.html#action10
     [30] http://www.w3.org/2006/09/19-htmltf-minutes.html#action01

   [DONE] ACTION: Ben announce new URIs for editors' drafts to TF
   [recorded in
   [31]http://www.w3.org/2006/10/16-htmltf-minutes.html#action04]
   [DONE] ACTION: Elias summarize the reification discussion [recorded
   in [32]http://www.w3.org/2006/10/16-htmltf-minutes.html#action11]

     [31] http://www.w3.org/2006/10/16-htmltf-minutes.html#action04
     [32] http://www.w3.org/2006/10/16-htmltf-minutes.html#action11

   [End of minutes]
     _________________________________________________________


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