[topicmapmail] SAM question

[Lars Marius Garshol]

* HERBUEL Alain
|
| TopicName : understood
| Type of a name : understood
| XTM 1.1 : Reading in progress! ;o)

Good. :-)
 
| Question : type of something in SAM
| * Topic may have a type

Actually, topics may have any number of types, but the topic-type
relationship is different from the other item-type relationships that
occurrences, associations, topic names, and association roles have.

A topic may have many types, and the relationship is expressed with an
association. Neither of those two things are true for the item-type
relationship expressed by the [type] property.

| * Occurrence may have a type
| * Association may have a type
| * TopicName may have a type (new with SAM)

Yep.

| * AssociationRole may have a type (new with SAM)

The only thing that's new is the terminology, really. This is what
<roleSpec> in XTM 1.0 expresses. What has happened is that the
committee has decided that the XTM 1.0 terminology of member and role
was bad, and so we've gone back to the original ISO 13250 terminology
of association roles and association role types.
 
| In 5.1 Type-instance relation, you describe a PSI
| (http://psi.topicmaps.org/sam/1.0/#type-instance
| <http://psi.topicmaps.org/sam/1.0/#type-instance> ) for special association
| "Type-instance".
| Is the [type] relation in SAM model a sort of syntactic shortcut to
| express the same thing (like InstanceOf in XTM)?

It expresses the <instanceOf> element when used directly inside a
<topic> element, but not when used inside the other elements that can
be typed. This reflects the difference between topic types and other
types discussed above.

The XTM 1.1 document shows this, since it shows how to build data
model instances from XTM documents.

Note that XTM 1.0 had the same model, though you have to read Annex F
very carefully to see it. See section F.3.2. The idea of using
associations to type occurrences and associations has been abandoned,
and IMHO that's a bug in XTM 1.0. (Consider how to type the
class-instance association that types the original association...)

-- 
Lars Marius Garshol, Ontopian         <URL: http://www.ontopia.net >
GSM: +47 98 21 55 50                  <URL: http://www.garshol.priv.no >