Re: One-To-One Relationships

On Nov 30, 4:19 pm, Jan Hidders <hidd..._at_gmail.com> wrote:
> On 29 nov, 23:16, JOG <j..._at_cs.nott.ac.uk> wrote:
>
>
>
> > On Nov 28, 8:43 pm, rp..._at_pcwin518.campus.tue.nl (rpost) wrote:
>
> > > paul c wrote:
>
> > > [...]
>
> > > >Regarding ER, here are some quotes from Codd's book (available for free
> > > >at acm.org). The sarcasm of the second one made me laugh.
>
> > > The criticisms you quote may be amusing, and they have merit, but
> > > they ultimately miss the point. 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).
>
> > I realise that others have attempted to point out your mistakes, but I
> > just wanted to echo their sentiment.
>
> How about providing some real arguments, in stead of just sentiments?
> Haven't seen much of those here and I think Reinier deserves them.

Feel free to offer some of your own for him instead of simply complaining.

>
> > There is absolutely no difference
> > between an entity and a relationship. E/R modelling has /itself/
> > conceded this, translating relationships into "associative entities".
>
> Ah, yes, and as we all know, if two concepts have overlap then they
> are actually the same. *sigh* The distinction between entities /
> relationships

Great, if this distinction is so clear feel free to elucidate the final word on the matter.

> domain objects / predicates is pretty well-established
> in linguistics, philosophy and logic. First-order logic, you may have
> heard of it, separates them even strictly.

Puh-lease Jan, this sort of thing is beneath you. There is no need to be so condescending. This is a usenet forum not ACM transactions, so there is always going to be loose debate. And anyhow, the question is not of the use of entities in FOL, but of a preffered role for entities in a logical data model.

> Are you now going to claim that it is no good for reasoning?

Who ever claimed that? Reasoning? Seems to me you are the first to mention the word. It is very unlike you to start trying to push words into peoples mouths, and I think we'd all normally expect better of you.

I am sure you don't believe that we should just accede that Jan has spoken and everything is already decided. Ought we just forgo all the / ongoing/ issues in identity research, because FOL has its own definition? Maybe you should have spoken to Geach before he wasted all his time on relative identity? After all Liebniz had already defined identity centuries ago right?

Was very disappointed in your post. If you think someone deserves a longer response, I am more than receptive to that being politely stated.

>
> -- Jan Hidders
Received on Fri Nov 30 2007 - 17:52:37 CET