Re: "Role of RSS in Science Publishing": Atom is in RDF format

[Henry Story <henry.story@xxxxxxxxxxx>]

Just found this mail and thought it worth replying to. It points out a 
little bug
with the Ontology I just released lately. I made the entry id inverse 
functional.
That won't do.

If id is inverse functional, then given two entries with the same id

_f1----a-----> <Feed>
  |---entry--> _e1 ---a-----> <Entry>
  |              |-----id----> <tag:example.com:2005_01_03>
  |              |---title---> "first verzion of the entry"
  |              |-published-> "20 Dec 2004"
  |...


_f1----a-----> <Feed>
  |---entry--> _e2 ---a-----> <Entry>
  |              |-----id----> <tag:example.com:2005_01_03>
  |              |---title---> "second version of the entry"
  |              |-published-> "10 Jan 2005"
  |...


One would have to conclude that the anonymous nodes _e1 and _e2 were 
the same.
Ie

    <tag:example.com:2005_01_03> -----1/id-------> _e

the inverse of id (called 1/id) can only have one value.

But if we tried to do this we would have to conclude that the entry with
<tag:example.com:2005_01_03>, called _e had two publication dates. Yet 
an
Entry can only have at most one.

So we end up with a contradiction by making id inverse functional.
By simply making it functional we bypass that problem, and we have 
correctly
model what we had: namely we have two Entries with the same id, which 
one can
think of as two versions of the same entry.

On 20 Dec 2004, at 18:45, Danny Ayers wrote:

> ...
> Some of the possible approaches for an RDF/XML expression of the info
> include (ignoring namespace decls & case!):
>
> RSS 1.0 style:
>
> <rdf:RDF>
>    <head/>
>    ...
>    <entry rdf:about="vemmi://example.org/2003/32397">
>       <title>Stuff</title>
>       ...
>    </entry>
> ...
> </rdf:RDF>

this would be equivalent to making id inverse functional. If you do this
then you have the merging problem explained above.

> -------------------------------------
>
> A bit more plain-XMLy :
>
> <feed>
> <head/>
> ...
> <entries>
>    <entry rdf:about="vemmi://example.org/2003/32397">
>       <title>Stuff</title>
>    ...
>    </entry>
> ...
> </entries>
> ...
> </feed>


yes this just groups the entries in an "entries" tag. I don't see that 
it
adds much. (I know you are just pointing out all the different ways one 
can
do this)

> ----------------------------
>
> Lumpier:
>
> <feed>
> ...
> <hasEntry>
>    <Entry rdf:about="vemmi://example.org/2003/32397">
>       <title>Stuff</title>
>    </Entry>
> </hasEntry>
> ...
> </feed>


note: the RDF people think that having properties named
hasXXX is quaint. Or so at least DanC told me on #irc quite a
few months ago.


> ------------------------------
>
> Closer to Atom 0.3 :
>
> <feed>
> ...
> <entry rdf:parseType="Resource">
>    <id>vemmi://example.org/2003/32397</id>
>    <title>Stuff</title>
> ...
> </entry>
> ...
> </feed>

This is exactly right, except that id should absolutely not be inverse 
functional.
Just functional will do :-)

> The last is kind of interesting, having the id attached to a blank
> node. If id were spec'ed as an inverse functional property that might
> work nicely.
>
> But as far as I can tell none fit too well with :
>
> <id href="vemmi://example.org/2003/32397"/>
>
> Cheers,
> Danny.
>
> --
>
> http://dannyayers.com