Re: On formal HAS-A definition

Nilone wrote:

>On May 7, 1:38 am, r..._at_raampje.lan (Reinier Post) wrote:
>> I don't think I'm bothered by that fact.  Belief in strong typing
>> tends to do that to you.  An employee just isn't a department
>> so why would an employee ever need to pose as one?
>
>It looks to me like tuples are being equated with entities.

When justifying the definition of IS-A in the E/R-model: yes.

>> This is neither aggregation (in the weak entity sense)
>> nor composition (in the cardinality sense).
>
>Yep, there's the entity.

It's a little difficult to talk about identity 'is a') without talking about entity ('is').

>A relation is not a domain.

THat is irrelevant for the IS-A I'm discussing.

-- 
Reinier