[sc34wg3] TMCL: 4.4.1 Topic Type Constraint
rho at devc.at
Thu Feb 14 03:37:55 EST 2008
On Thu, Feb 14, 2008 at 07:40:53AM -0000, Graham Moore wrote:
> >> How is 4.4.1. to be understood?
> >> "..only topics ... defined as topic types can have instances"
> >> What about association types, occurrence types and name types? They
> >> definitely need to be "topics allowed to have instances".
> Firstly, this is a map wide constraint.
Yes, many constraints in TMCL are map wide.
> It is trying to say that if a topic plays the role of type in the
> type-instance association and it is NOT an instance of the topic
> tmcl:topic-type that the given type topic violates the topic type
> .... The evaluation function knows the topic of topic-type (its
> defined in TMCL) and can thus derive the list of all topic types at
> evaluation time.
Hmm, 4.1. says that "Constraints are independent from each other....",
but obviously TMCL somehow makes a distinction between allowing to say
"Person isa tmcl:topicType"
and the actual TopicTypeConstraint which is sort-of hovering in the
background. I didn't get this from the text. But my interpretation
> uniq ( // tm:topic >> types ) -- // tmcl:topicType == null
would then reflect this. Good.
> I'm not sure I follow the bit about having to adopt the tmrm-tmdm
> mapping stuff. TMCL aims to be self contained in terms of TMDM and
> TMRQL. Given we can identify the topic-type topic we don't need the
> tm:topic in order to formulate the query.
Well, TMQL _has_ to use TMDM and needs hooks to get access to the
innards of a map.
> Hope this starts to clear some things up.
We still have to say something about making the fact
Person isa tmcl:topicType
accessible to the TMQL processor which effectively checks the map.
Austrian Research Centers, Environmental Monitoring Systems
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