Re: [xtm-wg] Issue with instanceOf

["Steven R. Newcomb" <srn@coolheads.com>]

> SN wrote:
> "A scope is a set of topics.  A scope is not a set of references to
> topics; it's a set of topics, full stop.  It's true that,
> syntactically, we refer to the topics in order to indicate that they
> participate in scopes.  But that's just syntax ..."

> Just for the purposes of exposition I'm going to resurrect the ISO-13250
> word 'theme' here. So my question is: Do the associations between topics
> that become themes matter in an s-node?

Yes and no.

Yes, because in a very real sense, a topic *consists* of roles played in
associations with other topics.  (This is especially obvious in the
graph.)  When you delete a topic's membership in some association, in
some sense you change what the topic is.

No, because if a topic were to somehow lose one of its memberships in
some association, perhaps because the association is deleted, its
memberships in various scopes would probably be completely unaffected.
I say "probably" rather than "certainly" because there is a
possibility that the deleted association might have the topic in its
scope, and it might be the only association in that scope, so the
s-node might go away, too.  In that sense, then, the question of the
existence of an association between topics might also be the question of
the very existence of an s-node.

> You say that an s-node is a set of topics, but I want to know
> whether that means that an s-node is implicitly a set of topics
> *and* any associations that exist between them in the map?

(We really need those diagrams now.  I'm sorry this is so confusing.
I can't explain this more clearly in plain text than I already have.)

> I.e. what *precisely* is at the 'scope' end of an 'association
> scope' arc?  What's in an s-node?

A node is just a nexus where arcs meet.  There's nothing "in" a node.

An s-node serves as the "scope" end point of two kinds of arcs: 

- "scope participant" arcs.  The other end of each such arc, the
  "participant" end, is a t-node (or a-node, because a-nodes are also
  topics) that is a member of the set of topics that constitutes the
  scope.

- "association scope" arcs.  The other end of each such arc, the
  "association" end, is an a-node whose scope is the set of topics
  that the s-node exhibits by virtue of the "scope participant" arcs
  at the "scope" ends of which the s-node appears.  All associations
  that have the same scope are connected by "association scope" arcs
  to one and the same s-node.

-Steve

--
Steven R. Newcomb, Consultant
srn@coolheads.com

voice: +1 972 359 8160
fax:   +1 972 359 0270

405 Flagler Court
Allen, Texas 75013-2821 USA

To Post a message, send it to:   xtm-wg@eGroups.com

To Unsubscribe, send a blank message to: xtm-wg-unsubscribe@eGroups.com