Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]
Date: 16 Jun 2005 11:13:23 -0700
Alexandr Savinov wrote:
> In COM:
> syntax = a set of concepts
> semantics = a set of items
> concept = a combination of superconcepts
> item = a combination of superitems
> and so on (please, do not ask me to continue because I am not able to do
> it here in the forum).
You are putting me in a difficult position by asking me not to question you any more, but I'll try anyway ;)
The word 'syntax' usage is highly unorthodox but let it stay, I'll consider it just a label.
- What's a 'superconcept' and how exactly you compose 'superconcepts' to produce a 'concept' ?
- What's a 'superitem' ? Is it the same as a set element ? Does it have a type ? How does one compose superitems to produce an item ?
In short, please give a short description of your data model and what
its advantages/disadvntages are in comparison to the RM. Please do not
use words from your private vocabulary, but if you do please define
Parenthetically, the word '[super]concept' is even more ambiguous than 'semantics' but if you are willing to provide a definition I can live with it.
> >>As far as I remember I explained that. Here is that definition again:
> >>- a value (a variable taking a value) = a possiblity distribution which
> >>is equal 0 (impossible) everywhere except for one point.
> > I am confused. How a value can be a function ? A value of a certain
> > type, say integer, is a member of the set of integers. Now, as you
> > know, a function is a a mapping between sets. So how can you say that
> > a value is a function ? Are you using a theory where the function is a
> > more primitive notion than an element of a set ? Please explain.
> I already mentioned that terms, especially general ones, may change
> their meaning. The terms value may be defined differently. In
> particular, it can be defined via membership *function*.
When one wants to use a word in some special sense, one has to provide a definition of one's own, doesn't one ? Now, what has the membership function has got to do with the stuff we are discussing ? Are you talking about, God forbid, fuzzy set membership functions, or do you have something entirely different in mind ?
> The term
> function can be applied to such a strange somewhat illegal construct as
> delta-function (which is not a function as you correctly noticed) and so
It can cannot it ? But how relevant the use is ? What does it add to the problem understanding I wonder ?
> It seems to me that we are talking about everything and nothing
>You vary the focus of the discussion arbitrarily
> hierarchically (between very general and very specific level) and
> multidimensionally (changing the direction within one level on 90
> degrees). So I am lost and do not understand where we are now.
Well, excuse me, it was not me was it who started throwing around the high-faluting words like singularity, delta-function, lattices and such ? I've just humbly tried to clarify what we were talking about that's all. I'd be happy to come back to the data model stuff.
Received on Thu Jun 16 2005 - 20:13:23 CEST