parid0157 | Mon, 18 Nov 2002 19:05:08
So I see what the constraint "No multiple role players of a single role type" enforces unto the representation in some cases, but I fail to see what problem(s) it solves. Particularly, I don't see how multiple players of the same role type can break Subject Location Uniqueness.
parid0157 | Mon, 18 Nov 2002 18:47:56
I agree with bernard, it is not clear in the RM how I model
symmetrical relationships. Such as his sibling example.
parid0157 | 18 Nov 2002 23:53:11
* Sam Hunting
| (2) Is the best/only way to model the prose statement "Hot and cold
| are opposites" an assertion with a single role player that
| represents the set {"hot","cold"}
That seems quite a funny way of doing it to me, and structurally
different from how topic maps represent this, which would more
naturally be
opposites(hot : opposite, cold : opposite)
In the SAM this is an association item with two role items in its
[roles] property. The transformation to the RM is more involved than
people will expect it to be, and it does seem a little odd.
I realize the rationale is that there should be a node that allows us
to speak about both at the same time, but I'm not sure what the
argument that leads from there to the construction of the set is.
parid0157 | Wed, 20 Nov 2002 08:43:50
> Why, though, is it necessary to define two different
> role types, even though one would do the job?
> The answer is that without the rules:
>  (1) that all role types must be different, and
This, I feel, is the role that is in error in the current RM.
>  (2) that there can be only one role player per role type,
This is the role that is actually needed.
> ...the Subject Location Uniqueness Objective can't be
> supported.
I cannot agree with this statement. SLUO can be supported more simply by
requiring the pair to be unique.