Hierarchical Model and its Relevance in the Relational Model

I have mentioned the two of you, and this issue, in a recent post. Far be it from me to snipe from the edges. I expect to deal with this matter squarely, so here is a new thread. Pasted here for your convenience:

...

> [Implementation of Data Hierachies is] simple for me, difficult-to-impossible for those who are victims of the suppression of Hierarchies, as a result of Date's, Fagin's, Darwen's, Abiteboul-Hull-Vianu's "work", and as proliferated by virtually every mathematician, eg. as evidenced by J Hidders and J K Lowden.

There are four parts to this, as it is addressed to two people: a common context; one part each, which is specific to each of you; and one common part addressed to both.

• 1 Context ====

> On Saturday, 3 January 2015 10:02:35 UTC+11, James K. Lowden wrote:
>
> "Nowadays it is accepted that ORM (Object-Role Modeling),
> Object Oriented (OO) and other post-OO methodologies, such as Agile
> Modeling, Agile Development (Erickson, Lyytinen, & Siau, 2005) are most
> appropriate not only for programming, but also for analyzing and
> designing information systems, including, of course, database design."
>
> Far from being "accepted" for the purpose, software development
> methodologies have exactly nothing to say about database design.

First let me say that I agree, and strongly. (I have issues with the exclusive wording, but that is irrelevant to this thread.)

> The
> author doesn't seem to know that that "OO databases" rest on the very
> same theoretical void that the hierarchical and network models did
> before them.

Let's get a couple of things out of the way, so that the scope of this thread is clear. - While there are a number of mathematical papers that propose or reinforce various OO theories, which is of course what the OO boys use to justify their creatures, I whole-heartedly agree that if one were to remove the un-scientific papers from that body, one is left with a void. - It is one of the main reasons that "analysing and designing" data, for either Relational or OO implementation, using OO/UML principles, is completely bankrupt. We are flooded, these days, with people using OO/UML to model what they intend to implement as a "relational database".

The Network Model, although very relevant, is not relevant to todays issues or to the Relational Model, so let's carve that off. So we are left with the theme of the thread: you have posted, and I paraphrase, that:

1. ____the Hierarchical Model rests on a theoretical void____

You did not state it, but the implication is, the HM is dead, gone the way of the NM. Therefore (again, I paraphrase):

B. ____the HM is dead, it has no relevance wrt the Relational Model___

• Aside --

> Yet if we discard the fancy language and
> ... mathematical exactitude ...

I had a good laugh at that one.

c.  you guys cannot even agree with each other (one man's proof is another man's void)
d.  you guys cannot differentiate base relations from views (derived relations), you are forever making the gross error of "normalising" views, and failing to "normalise" base relations.  "Normalise" is in quotes because you guys have your private "definitions", so I happily allow whatever you mean by the term, it is not intended to be an insult.
e.  you guys insist that you know the RM, but are forever producing evidence that you do not
f.  you will not allow yourselves to be pinned down on any single point, ie.  you avoid exactitude.

• End Aside --

> That's part of the beauty of the [Relational] model and why Codd developed it:
> relations are easy to understand and develop intuition for.

Agreed, completely.

F. The implication here, and in many other places, is that you know the Relational Model, and you know it well.

That is the scope, I hope I have identified it clearly.

• 2 James K Lowden ====

If you are unhappy with my paraphrasing, please feel free to supply your own precise statements. Assuming you accept the paraphrasing as accurate:

1. I take issue with your proposal [A]. I charge that it is completely and totally false. But that is not as important as the implication [B], which is totally and completely false.
2. Further, I charge that the belief [A][B] of which, substantially damages and hinders (i) the understanding of, and (ii) the application of, the RM.
3. There is a statement implied in [1][2], which I will make explicit. I declare, the Relational Model is not a replacement for, or a substitution for the Hierarchical Model; it is a progression of it. The RM was not concocted in isolation, in the far reaches of outer space. (Let's not mince words, of course, something that is a progression of its predecessor, something that is far superior, replaces the predecessor. However, the predecessor remains a fundamental part of the successor, and is visible in it.)

Given [F]; your valuable advice to seekers; your demonstrated concern for accuracy, which I support, I suggest you should respond, with: - either a retraction of [A][B]
- or some real world evidence supporting [A][B], which thus far has been stated without evidence

• 3 Jan Hidders ====

You have made several statements re the Hierarchical Model, in several posts, pretty much along the lines JKL. I did search, and I did not find a post that states anything squarely (it is always an indirect reference [not suggesting that such was wrong, it may have been quite appropriate for the context] ). But in any case, I think I am reasonably correct in identifying that you sit in the same position as JKL on this matter. If you are unhappy with my paraphrasing, please feel free to supply your own precise statements. Assuming you accept the paraphrasing as accurate:

I believe you agree with [A][B]. Unquestionably, [F] applies to you. So I am taking it up with you as well, I make the same charges, and the same declarations [1][2][3].

If you understand me, and agree that I have picked up your position re the HM:RM accurately, your comments about [F] accurately, then simply proceed, skip this next section.

• 3.1 JH Specifics --

Iff you want something specific, as a starting point, try this post: https://groups.google.com/d/msg/comp.databases.theory/r3BHhq1EFbs/iE5AIvLD6BYJ

The context of the thread, and your post itself, are not the issue, it is the statements/references/implied-statements that you made re the HM, and its value in the RM context, that I wish to take up:

4.
> On Sunday, 21 April 2013 23:35:37 UTC+10, Jan Hidders wrote:
> >
> > [RM and ERM are the context]
> >
> > http://en.wikipedia.org/wiki/Structured-Entity-Relationship-Model
>
> Right. SERM. Part of Aris, a SAP thing. The hierarchical database
> model, once again trying to make a come back in a new disguise. :-)

I declare, the HM (or the "hierarchical database model") never left. It has always been here. It therefore cannot make a comeback.

Please feel free to submit any evidence otherwise.

5.
> > [Rule: Circular references are not permitted]
>
> The German page is more explicit and does mention this rule.
>
> > Which appears to be a perfectly reasonable rule to me ...
> > Is it perfectly evident that this requirement must be enforced, since a
> > model with cyclic dependencies is plain "spaghetti", maybe even
> > violating some normal form?
>
> It has nothing to do with normalization in the classical relational
> theory sense of the word.

I declare, it has a direct and definitive relationship with Normalisation, as defined in the RM.

Please feel free to submit any evidence otherwise.

(Forget about "classical relational theory sense of the word" [AFAI am aware, "relational theory" does not deal with Normalisation, but hey, I am not a mathematician. But that is not the point I wish to take up.] I am dealing with the RM.)

• End Specifics --

Clearly, from your various papers as well as posts, [F] applies to you, you are a prolific author in the OO/ORM/RM (ok, theory only) space, you are a teacher at university level, transferring knowledge to many young minds, therefore I expect you to take it up responsibly. Obviously, I support that, the transfer of accurate information. I suggest you should respond, with: - either a retraction of [A][B]
- or some real world evidence supporting [A][B], which thus far has been stated without evidence.

• 4 Further Context ====

In case it is not obvious, I am not interested in mathematical proofs. As one of my professors said, decades ago, a mathematician can prove that pigs can fly, it is up to you [as a scientist] to prove that they actually do. Therefore (a) in the first instance, let's avoid that skirmish, (b) but if you want it, I will engage.

In the event that there is a discussion, I too will be supplying real world evidence to support my statements, not mathematical proofs.

Mathematical proofs are only a fraction of the theory (the "t" in c.d.t). Theory is only a fraction of the science. I would like to limit the discussion to science. That means hard evidence, no "convincing", no "beliefs", which is the ambit of non-science; cultists; jehovah's witnesses, and which requires private "definitions'; use of private "bibles"; etc.

I am discussing the ***Relational Model***, and statements you have made about it, and its componentry, including the relational theory in it, as published. I am *not* discussing what mathematicians call "relational theory", which apparently has completely different descriptions (no definitions AFAIK), algebra, calculus, etc, which perhaps existed before 1970, and in any case, is not in agreement with, and bears little relation to, the RM. So please, let's not get side-tracked, dragged into RT or the RM::RT delta. The statements made were about the RM. - if your statements were about RT, and were applied to the RM as a result of sloppiness, then it is a simple matter for you to correct the sloppiness, and state that they do not apply to the RM.

I appreciate that I am a practitioner, in the real universe, and that you are abstractionists, in the unreal universe. But you have made statements re the RM; the HM; which most definitely exist in the real universe, that cause problems for many people (eg. the referenced Topological Algebra post), which I wish to resolve once and for all.

• Alternative --

I will also give you an alternative (to supplying evidence to support your statements, and the predictable results). After you retract them, redress __the void in your profession re the Relational Model__ extant for forty four years, and write a formal paper, complete with mathematical proofs, that /formally/ defines the two Normal Forms that are /informally/ (but quite usefully, for practical purposes) defined in the Relational Model. As a "lay person", the obvious names for them are: ____Hierarchical Normal Form
____Relational Normal Form
If you take this up, I would be pleased to supply more context, and directions, in order that you avoid the infamy of frauds (such as Date, Fagin, Darwen, Abiteboul-Hull-Vianu), and you gain instead fame, in the physical universe. You might achieve the ACM Codd Award.

This is a public notice. I will endeavour to find your email addresses, and to email this to you as well.

I await your considered response.

Cheers
Derek Asirvadem Received on Wed Jan 28 2015 - 10:52:59 CET