Re: Proposed simplification of datatype expressions

I'm not sure if Ian's proposal rules out the possibility of saying "more
than 1," but if so, I can think of a number of examples of these:

- the class of all people with more than one middle name
- the class of people with more than one alias
- the class of products with more than one advertised price

Specific numbers are a little harder. Maybe saying something like a
triangle has exactly three values for its angle property? You could
probably come up with a number of examples like this for CAD or
geo-spatial database applications.


Peter Crowther wrote:
> > From: pat hayes []
> >
> > >"people who have at least three values for property x."
> > >
> > >where x is a data valued property. I, too, struggle to think
> > of an example
> > >where one would actually want to use such a construct (but am open to
> > >suggestion)....
> >
> > People who own three or more homes, people with at least three
> > sources of income, people with at least three children, people with
> > with at least three nationalities, people who have travelled to more
> > than three foreign nations during the last six months,....
> All good examples of cardinality contraints to objects; I have to say
> that I'm not convinced that any of the following are naturally
> datatypes:
> - homes
> - sources of income
> - children
> - nationalities
> - travel to a given nation during a date range
> Nationality, in my view, comes closest; but why is this better as a
> datatype than an object?
>                 - Peter

Received on Monday, 17 March 2003 09:47:02 UTC