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Re: Microsoft and the two great blunders

From: Alfredo Novoa <alfredo_at_ncs.es>
Date: 28 Dec 2003 12:00:37 -0800
Message-ID: <e4330f45.0312281200.406f3000@posting.google.com>


Costin Cozianu <c_cozianu_at_hotmail.com> wrote in message news:<bsgq38$cmb87$1_at_ID-152540.news.uni-berlin.de>...

> They don't say give me a relation of customers either.

Here they do all the time.

> > But my main complaint is about using a single word for table value and
> > table variable. They are fundamentally different concepts.
> >
>
> Who's using that ?

Everybody who use the term.

> > Table is more appropiate for the SQL bags, and relation is more
> > appropiate if you are talking about a relational database.
> >
> Ahem, you mean relvar ?

No, relation is the short for relation value and relvar is the short for relation variable.

> > I have never seen a table containing all the values of a tuple type at
> > practice. In many cases it would be physically impossible.
> >
>
> All the values in the domain of interest that are of a certain type. For
> example all the value of Employee type.

The number of values of the Employee type is virtually infinite!

> > It does not have relationship with the great blunder.
>
> Oh, but that is allegedly one of the great blunder. Read TTM appendix.

No, you are misunderstanding it.

> > Any operator may be a part of several types, and you can express that
> > without problems with that template (and flawed) grammar.
> >
>
> So if an operator is part of several types, you've got a problem. Are
> operators part of the type definiton or not ?

You are mixing apples with oranges. The proper question should be: Are operators definitions part of type definition? And IMO the answer is yes.

But one operator may be shared by several types.

> >>TYPE ELLIPSE
> >> IS PLANE_FIGURE
> >> POSSREP { A LENGTH, B LENGTH, CTR POINT };
> >
> >
> > It is not a complete type definition.
> >
>
> So what would be the complete type definition ?

The operators definitions are missing.

> Oh. But
>
> type Plane_Figure union;
>
> Is void of content.

Because we have not added the operators definitions.

> A proper abstract data type is something entirely
> different

I meant it is similar to an "abstract class".

> What *is* Plane_Figure , and what's the purpose of that declaration ?

A union type. A supertype for all plane figure types. It does not have a representation, but it may have operators. It may resemble to a Java "interface".

> IMHO your knowledge of the entire subject of type theory is weak.

Surely, but we are talking about very fundamental things. I don't need to master type theory in order to know that types are not variables.

> >>Nobody is confusing anything.
> >
> > Then we live in different worlds.
> >
> > Have you readed this:
> >
> > http://www.ambysoft.com/persistenceLayer.pdf
> >
> > It is the inspiration of dozens of SourceForge and comercial projects.
>
> So what ? People are free to waste their time however they wish.

So many people hardly can be more confused and misleaded. But of course they are very free to waste their time and the resources of their employers.

> > Entity-types are virtually meaningless. Is the E/R "model" your idea
> > of a formal framework? }:)
 

> Yes, it is. A little bit of reading on the subject wouldn't hurt you.

It is hilarious. The E/R model is a well known paradigm of formalism lack.

> > It is clear on the slides.
> >
>
> So you still haven't shown any problem.

It was never my intention. I thought that the problems would be very clear to the educated readers of the group.

Regards
  Alfredo Received on Sun Dec 28 2003 - 14:00:37 CST

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