[sc34wg3] Re: [topicmapmail] Multiple scopes on associations

Martin Bryan sc34wg3@isotopicmaps.org
Tue, 23 Oct 2001 08:12:39 +0100

Lars Marius Garshol wrote

> I think I've understood this now. You want to know what happens when a
> <mergeMap> element with added themes refers to a topic map containing
> an association with a non-empty scope.

Exactly. My concern is that both added themes and local scopes can refer to
multiple topics (sets of topics) and the question that seems to have arisen
is one about whether or not combining these creates a set of sets, or a
single set.
> These are the different alternatives, as far as I can tell:
>  - ISO 13250: the added themes are added to the single scope of the
>    association
>  - XTM 1.0: ditto, according to
>    <URL: http://www.topicmaps.org/xtm/1.0/#elt-mergeMap >. Note that
>    this says "the scope", clearly implying that characteristics have
>    but one scope.
>  - Infoset model: ditto, as described in
>    <URL: http://www.y12.doe.gov/sgml/sc34/document/0242.htm#d1e1076 >.
>  - PMTM4: the added themes are connected to the s-node the association
>    already has, and no new s-node is created for them. (I think.) This
>    is equivalent to the statements above, just expressed using a
>    different formalism.
> In short, the four 'specifications' all seem to agree on this.

So as I understand it there is no difference between any of the models. The
only difference is whether or not two different sets of scopes/themes
attached to associations that link the same topics using the same
association identifier are considered to be the same association with
multiple scopes or a set of associations. My question then is "Does it
really matter which way applications store the data, as long as we
understand that a given pair of topics can be linked by the same association
type multiple times in different scopes?". (For example, A can be married to
B more than once. As long as the scope of each marriage is differentiated
then there should be no problems distinguishing them.)