Re: RM formalism supporting partial information

From: David BL <>
Date: Thu, 15 Nov 2007 11:11:26 -0800 (PST)
Message-ID: <>

On Nov 16, 2:54 am, Jan Hidders <> wrote:
> On 14 nov, 14:47, David BL <> wrote:
> > Nearly two weeks ago I posted to the thread "atomic" regarding a join
> > operator I had defined back in January. A discussion with Paul C
> > inspired me to more carefully develop the mathematical formalism.
> The mathematical formalism is not your biggest problem, altough it
> could certainly be improved (if you want I might be tempted to help),
> but what seems to be missing is a decent understanding of what all the
> math exactly means. What is the intuition behind your approach? Why
> would it make sense? You hint at this with the interpretation function
> I, but this should not be a side remark in the middle but rather the
> foundation and justification of the rest, and that doesn't seem to be
> there.

I agree the document leaps straight into the maths without properly stating the objective, and I don't consider it in any way suitable for publication. I wanted to talk about the meaning and purpose on cdt, and the document was really more like a "dumping ground" because directly posting that stuff wasn't a good option.

You are correct that the interpretation function I is the "foundation and justification of the rest".

I would certainly be interested in any suggestions on how to improve the mathematical formalism. Perhaps you could post an example of what you have in mind.

I posted a work in progress in the hope that someone could offer some opinions - perhaps before I wasted too much time buried in the proofs. I would say as well that I regard the exercise as exploratory, and therefore it is difficult to say for what it might be useful without first discovering all the properties of the operators.

> It will not suprise you to learn that the use of the nested relational
> model as a representation for uncertain data is not really a new
> thought. I could give references, but you may want to Google yourself
> first, or maybe not because it might spoil the fun.

I've read about RVAs in ch 19 of C.J.Date's Introduction to Database Systems, as a possible solution to missing data. Is that what you are referring to?

> You may also want to Google my name, to see why I think I can get away
> with being so arrogant. ;-)

I don't think you're being arrogant at all.

> > There is far too much detail to post. The following is a link to a MS
> > word document.
> >
> A final tip. Decent database theory doesn't come in Word. It comes in
> LaTeX. :-)

I'm sure your time is precious and I don't want to be presumptuous, but have you digested much of the document? Do you have any particular comments on the operators, such as the information comparison operator which gives a partial ordering and a concept of information equivalence?

The union and intersection operators I defined appear to have nice properties and a straightforward interpretation. This seems to contrast with outer intersection and outer union. Does that suggest there could be something useful in the approach? Received on Thu Nov 15 2007 - 20:11:26 CET

Original text of this message