[sc34wg3] TMCL: 4.4.1 Topic Type Constraint

[Graham Moore]

Morning Robert, 

>> I have worked through TMCL this morning and have many (!)
questions. Too many for one email. So this is against the draft

Super!

>> 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.

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
constraint. 

The AssociationType, OccurrenceType, NameType, RoleType constraints are
all aiming to do the same thing. Highlight where in the map people have
used a topic as an association, role, name, etc type without marking it,
as an instance-of, one of TMCL association-type, role-type, name-type
topics.

>> Which implies that such a constraint has to parameterized with
a list, not a single topicType, right?

No. 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.

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.

Hope this starts to clear some things up.

Graham

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Editor XTM 1.0, ISO13250 (TopicMaps) -2,-3, TMCL
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-----Original Message-----
From: sc34wg3-bounces at isotopicmaps.org
[mailto:sc34wg3-bounces at isotopicmaps.org] On Behalf Of Robert Barta
Sent: 13 February 2008 21:31
To: Discussion of ISO/IEC 13250 Topic Maps
Subject: [sc34wg3] TMCL: 4.4.1 Topic Type Constraint

Hi,

I have worked through TMCL this morning and have many (!)
questions. Too many for one email. So this is against the draft

  http://kill.devc.at/system/files/tmcl.pdf

--

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".

So what it may mean:

  "Except association types, occurrence types, name types and one
   particular topic (which has been marked as topicType), no other
   topic in a map may have instances."

But that of course still would rule out a second topicType, right?

So what it probably should mean is:

  "Except association types, occurrence types, name types and a
   list of topics marked as topicType, no other topic can have
   instances."

Which implies that such a constraint has to parameterized with
a list, not a single topicType, right?

A TMQL expression would then look like this

  uniq ( // tm:topic >> types ) -- // tmcl:topicType == null

It finds all instances of topics (so not assocs, ....), finds their
type(s), makes everything unique, reduces the list by those things
which we defined as topicType and NOTHING (null) is allowed to be
left.

This assumes

  (a) that we adopt the meta-ontology of the TMDM->TMRM mapping which
      defines subject, topic, assoc, occurrence, name

      http://kill.devc.at/system/files/2007-11-20-tmrm.pdf (page 13)

  (b) the tmcl:topicType and the marking that some topics are instances
      of it are in the 'same' map. But TMCL stays silent about that.

      So maybe

       " TMQL expression will be evaluated on the merged .... yada
	yada ..."

Else:

- first sentence has two dots ..

- ad example: ...and [is] added ... as it [is] considered [to be] ...

- ... if it needed to be ... this is just cryptic

\rho
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