Re: [topicmaps-comment] mapping topic maps on a relation database

["Thomas B. Passin" <tpassin@comcast.net>]

[Steve Pepper]

> At 09:32 17/04/02 -0400, Thomas B. Passin wrote:
> >[franck legoux]
> > >
> > > Does someone has a model to map "topic maps" on a
> > > relational database ?
> >
> >...
> >
> >2) How to handle multiple role-playing topics with the same role
>
> Unless your application needs to be able to preserve the exact syntactic
> form of the input topic map (in which case, I wish you luck :-), you can
> simply exploit the rule in Annex F of XTM 1.0 relating to "Equivalence of
> Multiple <member>s of the Same Role" (F.3.3) which states that:
>
> "An association containing multiple members, M1 and M2 of the same role R
> may be equivalently defined by an association containing a single member
M3
> of role R whose set of players is the union of the sets of players of role
> R in members M1 and M2."
>
> If your input document contains a <member> element containing multiple
> role-playing topics, you simply treat it as multiple <member> elements
> (with the same <roleSpec>), each containing a single role-playing topic.
>

Right, but it requires yet one more many-to-many relationship table and yet
that much more complexity in queries.  Probably there is no help for it,
though.  I have never really analyzed potential relational models very
carefully, so I don't know if there are some simplifications that can be
made here.

Cheers,

Tom P