[xtm-wg] Conceptual Model additional material

[Daniel Rivers-Moore <daniel.rivers-moore@rivcom.com>]

First may I apologise for the amount of email traffic the group has been
subjected to in recent exchanges I've been involved in. I needed to let the
group know I have technical issues to raise, and to express my concerns that
we not let time pressures stand in the way of these issues being properly
discussed. I did not intend these remarks to be seen as disputatious or
obstructive. I have no wish to delay the process of getting the spec out,
and am sorry that this may have appeared to be my intent. It was not.

Enough said  on that score. I promised I'd expose to the group the technical
issues I'm talking about, so we can proceed with the proper process of
assessing them on their merits.

I'd like to do this in three parts. First, in this email, regarding the
conceptual model. Then, in another mail I hope to complete before the end of
today, regarding the syntax. Finally, I have a few comments on the
processing model document, which I'll get to you as soon as I can - probably
early next week.


In an email to the editors during the days prior to Washington, I sent an
amendment to the section of the Conceptual Model text entitled "Associations
Relate Topics Within a Scope", and an additional section entitled
"Association Templates Define Classes of Association". Each is accompanied
by a UML diagram in .gif format.

The diagram and text on Associations rename the "Membership" box in the UML
diagram of association, calling it "Role" instead. The function of this box
remains essentially unchanged, but the explanation becomes clearer with the
revised name, and the text has been modified accordingly. There is no change
to the substance of the conceptual model for Association as it appears in
the current Review specification, but the explanation is, I believe clearer
in its new form.

The diagram and text on Association Template were not included in the Review
specification. I had submitted an earlier version to the entire group,
together with a section on the notion of an Association Prototype. As a
result of discussions with the editors and with other members of the former
Conceptual Modelling Subgroup during the week prior to Washington, it was
agreed that the notion of Prototype was not needed in XTM 1.0 and needed
further thought development if it were to be included in some later revision
of XTM. However, the notion of Association Template was agreed to be
fundamental. The reason the text and diagram were not included in the review
specification is that some late changes needed to be made to it, based on
clarifications emerging from the processing model discussions, and the
revised version of the text and diagram I submitted were too late for
inclusion. The text and diagram I sent at that time are included herewith,
and should  be added to the Conceptual Model in order to make it complete
and self-consistent.

The complete text is given below. The two images are attached.

Kind regards

Daniel

= = = = = = = =

REVISED AND ADDITIONAL TEXT FOR CONCEPTUAL MODEL SECTION OF XTM 1.0 (to
replace current section entitled "Associations Relate Topics Within a
Scope")



### Associations Relate Topics Within a Scope

Topics may be related to one another as players of Roles in an Association.
An 
Association has one Role for each way in which Topics may be involved in it.
For each 
Role, there may be zero or more Topics that play that Role. The Association
is itself a 
Topic whose Subject is the relationship between the Subjects of the Topics
that are 
players of its Roles, and each Role is a Topic whose Subject is the role
played in the 
relationship by those Subjects. The Scope, if present, serves to limit the
context within 
which the Association is valid.


#### Association between Topics (class diagram)

<img src="cd.AssociationBetweenTopics.gif"/>


### Association Templates Define Classes of Association

An Association Template defines a class of Associations characterized by the
Roles 
that it has and the classes of thing that can play those Roles. The
Association Template 
is itself an Association whose Roles are in one-to-one correspondence with
the Roles of 
the instance Associations that conform to it, and the players of whose Roles
are classes 
of which players of the corresponding Roles in the instance Associations
must be instances. 
Any player of a Role in the instance Association must be an instance of at
least one class 
that itself is a player of the corresponding Role in the Template
Association. An Association 
Template for marriage, for example, may have two Roles, 'may-be-husband',
played the class of 
men, and 'may-be-husband', played the class of women. Any instance
Association that conforms 
to this template would have a husband role, whose player must be an instance
of the class 
that plays the role of 'may-be-husband' in the AssociationTemplate, and a
wife role, whose 
player must be an instance of the class that plays the role of 'may-be-wife'
in the 
AssociationTemplate. In other words, the husband in a marriage that conforms
to this template 
must be a man, and the wife must be a woman. In a different society, the
'may-be-husband' Role 
in the marriage Association Template may have two players, the class of men
and the class of 
boys, and the  the 'may-be-wife' Role in the marriage Association Template
may have two 
players, the class of women and the class of girls. This would mean that the
husband in a 
marriage that conforms to this template must be either a man or a boy, and
the wife must be 
either a woman or a girl.</p> 

####Association Template (class diagram)
<img src="cd.AssociationTemplate.gif"/>


 <<cd.AssociationBetweenTopics.gif>>  <<cd.AssociationTemplate.gif>> 

-------------------------- eGroups Sponsor -------------------------~-~>
Big News - eGroups is becoming Yahoo! Groups
Click here for more details:
http://click.egroups.com/1/10801/0/_/337252/_/976895770/
---------------------------------------------------------------------_->

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

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

cd.AssociationBetweenTopics.gif

cd.AssociationTemplate.gif