Re: In an RDBMS, what does "Data" mean?

"Paul" <paul_at_test.com> wrote in message news:dNSAc.16737$NK4.2930587_at_stones.force9.net...

> For example:
> From 'Alan is in dept 20' and 'dept 20 is on the second floor'
> we can use semantics to deduce 'Alan works on the second floor', which
> is a totally new predicate. I suppose we are implicitly defining a view
> or new predicate like

In this particular case, your deduction depends on some real world knowledge. In particular, it depends on what the meaning of the word "is" is. (Clinton). It's not obvious to me that Alan works where the department he belongs to is located.
It's not obvious to me that Alan works at all. (Not a comment on the "Alan" who posts in here, BTW). :-)

But even taking it for granted that Alan works somewhere, it's not obvious that that somewhere would be on the second floor. Not obvious at all. In the corporations where I've worked (or at least, where I've "been"), there are departments, like accounting, that have people scattered all over the company. They also have a location where the department's headquarters are.

So Alan could be in the accounting department, and the accounting department could be on the second floor, and Alan could work on the fifth floor.

One place I worked, they referred to a person's desk as the place where that person "sits", not the place where that person "works". The implication wasn't that nobody works, but that people work away from their desk.

I'm sorry to be so nit picky about the meaning of words, but there actually is a point here. The point is that the deduction of inferences from existing facts is a whole lot more subtle than I think you are making it sound. It's possibly so subtle that the boundary line between first order logic and higher order logic is not as cut and dried as you are making it sound. Received on Sat Jun 19 2004 - 11:00:06 CEST