Re: Another view on analysis and ER

From: David Cressey <cressey73_at_verizon.net>
Date: Fri, 07 Dec 2007 13:27:14 GMT
Message-ID: <SSb6j.10853$3W.3518_at_trndny04>


"mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message news:475941b3$0$235$e4fe514c_at_news.xs4all.nl...
> Sorry for butting in this late, and not even completely on topic.
> 'Facts' triggered my interest.
>
> Jon Heggland schreef:
>
> > ...(The idea of viewing a database as a
> > collection of facts was a revelation for me in that regard.) In fact, I
> > have the opposite problem; I am unable to look at an E/R diagram without
> > thinking about relations.
> >
> > Consider this proposition: "Jon was born in 1974", encoded in a relvar
> > of the form Born(Person, Year). I think we'll agree that represents a
> > fact about Jon. You would probably assume that Jon is an entity (though
> > I'm unsure about what you'd call the relvar/predicate in itself---is it
> > an entity (type)?). But I would also say that the proposition is as much
> > a fact about the year 1974! Is 1974 an entity? I really don't care.
> > Facts are all.
>
> Consider the statement "Jon is 33 years old". It conveys the same real
> world fact in a clumsier way than "Jon was born in 1974". Next year it
> won't even convey the same fact anymore. "Jon was born in 1974"
> catches the invariant better than "Jon is 33 years old".
>
> Consider "John is in Canada". When? The fact isn't
> complete without that piece of information.
>

Time for a Clinton moment. The above discussion depends on what the meaning of the word "is" is.

In Spanish, "John is 33 years old" will be expressed roughly like this: "John has 33 years."
The verb "to be" is not used.

"John is a man" will be expressed using one of the Spanish verbs "to be".

"John is in Canada" will be expressed using the other of the Spanish verbs "to be".

This distinction is wasted on a person who thinks about the facts in English. But it isn't wasted, at all, on a person who thinks about the facts in Spanish. There are even statements in Spanish that differ only by which verb is used.

To a Spanish speaker, the following are two different facts: "Juan es loco."
"Juan está loco."

Does this mean that the content of the database is different, depending on the first language of the observer?

I apologize for using Spanish rather than a more common language. Spanish is the only language, other than English, that I know well enough to use to illustrate the point.

I recall that Bob Badour attributed to Dijkstra the motto that one should always do computer science in a second language. Received on Fri Dec 07 2007 - 14:27:14 CET

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