Re: One-To-One Relationships
Date: Sat, 1 Dec 2007 08:58:35 -0800 (PST)
Message-ID: <2704215c-2534-43ae-970e-7d6aefb67d76_at_d27g2000prf.googlegroups.com>
On Dec 1, 4:52 pm, rp..._at_pcwin518.campus.tue.nl (rpost) wrote:
> Bob Badour wrote:
>
> [...]
>
> >> [...] The distinction between entities and
> >> relationships: entities have identity (they can be referred to; attributes
> >> can have entity-valued domains), while relationships do not (they are
> >> completely identified by their, possibly entity-valued, attributes).
>
> >Except that relationships have identities too.
>
> By (my) definition, they do not.
Relationships /must/ have an identity otherwise how do you know they exist? This isn't metaphysics, it's set theory.
Consider the set {1,2,3} and a "less than" ordering over it , {(1,2), (1,3), (2,3)}. The identity of each individual relationship instance is articulated by its contents. Saying relationships have no identity makes no sense. How exactly are you defining identity?
> [snip]
Received on Sat Dec 01 2007 - 17:58:35 CET