Rick Marshall wrote:
> definition: an association is a meta structure that describes how two 
> data sets relate.
>
> in the example
>
> <Vineyard>
> <Lots>
>    <Lot id="lot1">
>      -- info about the lot --
>        </Lot>
>    ...
>    </Lots>
> <Pickers>
>    <Picker id="John">
>      -- info about the picker --
>        </Picker>
>     ...
>    </Pickers>
> <Assignments>
>    <Assignment type="isBeingPickedBy">
>        <participation type="Picker" idref="John"/>
>        <participation type="Lot" idref="lot1"/>
>       </Assignment>
>    ...
>    </Assignments>
> </Vineyard>
>
> needs a bit more work, but it's starting to be a structure that can be 
> inverted and easily answer lots of questions like who's picking in lot 
> 1? what is john doing? etc
>
> now the couplings are explicit and can be easily manipulated.
>
> could be done just as well with rdf (in this structure) but a bit 
> harder to read :)

If you're interested simply in describing associations, you could use 
UML. If you need to perform inferencing over the associations, and you 
don't want to write the reasoning engine itself, you might be 
interested in OWL. RDF doesn't really help you in either of these 
goals, as it assumes that the vocabulary and semantics of the 
relationships has been agreed upon.
--  
Chris Burdess