Re: One-To-One Relationships

On Nov 30, 9:36 pm, Jan Hidders <hidd..._at_gmail.com> wrote: [snip]
> You want me to explain the difference between the notion of "thing"
> and "fact"?

Yet /again/ you are put new words in my mouth. I never mentioned the word "fact" in this context. I asked you to elucidate the distinction between 'entity' and 'relationship', following your condescending statements (and *sigh*'s) that the issue has been resolved, inferring that not just me, but everyone involved in the debate here was foolish even to be discussing it. So now you have cleared the floor so everyone in CDT can hear you offer that final, unequivocal answer you claim exists.

[Quoted] Why don't you first define the term entity, as opposed to just assuming their existence as axiomatic. I look forward to there being absolutely no room for debate or disagreement! Look, you get a lot of respect on this forum, particularly off myself, but this does not excuse arrogance, so now we are all ears.

> Every fact is also a thing, but not everything is a fact.
> More precisely, a fact is an instantiation of a predicate where all
> roles have been filled in by things and which is true. That kind of
> thing?
>
> > > 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.
>
> You do realize that your response to Reinier also had that ingredient,
> don't you? Although others were far more worse. .

So others were far worse yet you jumped on mine, because of my renowned impoliteness? Or perhaps the constant personal attacks I dish out!? Or perhaps you just considered myself an easy target? If my post came across as churlish I would expect you to know from my previous posts that it wasn't the intention, and be polite in pointing it out.

> Reinier has given these matters more thought than you may realize

Ok, so how do you know that...

>
> > 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.
>
> I don't think so. The ER model places entities and relationships on
> equal footing. On the contrary, I would claim that the RM is
> unbalanced and focuses too much on the relationships.

You don't think I was talking about the best role for entities? What? Indeed I was sir. I have no idea why you are you now talking about the RM, when I have made no mention of it. It seems you are assuming my intentions.

>
> > > Are you now going to claim that it is no good for reasoning?
>
> > Who ever claimed that?
>
> I didn't say you did, I asked whether you were going to.
> It seems to
> follow from what you claim.

"Seems" to follow? I have said /numerous/ times recently that I believe that entities are useful at the conceptual level, following extraction from the logical model, and yet you now say I believe "entities are no use for reasoning?" Have you just seen a red mist and lost all of your normal cogent thought?

> If the distinction is not useful and in
> fact bad for data modeling then this should somehow become apparent
> when you start working with such data models.

But it is very apparent Jan. A testament to that are the hundreds of students I have encountered who end up very confused at the logical layer because of it (and their pre-indoctrination in OO), dropping the subject area as a result.

> After all, if it doesn't
> then it becomes hard to maintain that there is actually a problem. And
> reasoning about data would seem a typical intensive use where you
> would start noticing that your data model is not what it should be.
>
> > I am sure you don't believe that we should just accede that Jan has
> > spoken and everything is already decided.
>
> No, absolutely not. If anything I'm here to stimulate debate and fight
> they the idea that Codd and Date have spoken and everything is already
> decided.

Again, then you are addressing the wrong person. I am far from the view that the RM is the end of the line.

> So accepting my opinion on authority is the last thing I
> would want. But I do reserve the right to sometimes be a bit contrary
> and try to tease people into a discussion. With some that works,
> others may get all defensive. :-)

Having seen your responses after some gentle ribbing about your XML/ xquery work I'd say you'd put yourself in the latter category too right!

>
> > Ought we just forgo all the /
> > ongoing/ issues in identity research, because FOL has its own
> > definition?
>
> Hm? FOL doesn't say much about identity. It just assumes you know how
> to tell which objects in the domain are the same or not.

FOL is based on Liebniz identity at its very heart, x = y -> AP [P(x) <-> P(y)]. How is that saying nothing about the identity of entities? And I still contend that questioning this notion of identity, and hence the nature of entities, is worthy of discussion.

>
> > 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?
>
> Not sure how that is related, but since you brought it up let me say
> that the ER model is a far better setting for discussions about such
> identity research than the relational model. The inheritance of
> identity. The notion of relative identity. The changing of identity
> with different roles or with time. All can be elegantly formalized and
> discussed in the context of ER models.
>
> > Was very disappointed in your post.
>
> I was very annoyed by yours. Call it even?

Hardly. My apology would be to rpost if he was offended. Your apology would be directed at me ;)

But yes, fine. I'm ultimately a jolly sort.

>
> -- Jan Hidders
Received on Sat Dec 01 2007 - 01:13:36 CET