[sc34wg3] New syntax for (binary) associations

Robert Barta rho at devc.at
Wed Feb 6 05:07:23 EST 2008


On Sun, Feb 03, 2008 at 12:50:37PM -0500, Dmitry wrote:
> Many  "isa" associations are time sensitive. Modeling "real world"  
> roles as TM types makes sense to me, because
> types allow  to describe rich context  of  "being".  "Real world"  
> roles become types "with parameters".
> "Employee" has parameter "list of organizations", "Project Manager"  
> has parameter "list of projects", etc.

Ok, this shifts away from CTM and is actually more a modelling
discussion. But an important one, me thinks.

It is definitely true that roles have something "typishness" on
them, but I still see a clear distinction between

  - the type of something

    That is tasked capture the "essence" of a thing.

  - and the role

    Modern programming languages also call this 'trait', 'mixin':

       http://en.wikipedia.org/wiki/Trait_(abstract_type)
       http://en.wikipedia.org/wiki/Mixin

    This is situational, contextual and that suits perfectly as role
    (type) in TMs.

> BTW, many topic mappers re-use topic types for roles, so we will
> probably have "Employee" and "Employer" defined as types anyway.

> so we will have something like this:
> 
> o:is-employed-by(o:Employee: X, o:Employer: Y)
> 
> o:Employee
>      isa o:TopicType

I definitely reserve the right to mock people when they do that! ;-)

\rho


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