comp.databases.theory Google Group

Re: compound propositions

r...@raampje.lan (Reinier Post) — Fri, 19 mrt 2010 22:31:35 UT

We don't. By the way, in my terminology, Date and Darwin aren't
scientists, and mathematics is not a science. Your terminology may vary.
I was just trying to make the point that how we define things
doesn't necessarily coincide with how we name them. Of course
it's very helpful to have consistent terminology.

Re: compound propositions

cim...@hotmail.com (Cimode) — Fri, 19 mrt 2010 22:01:29 UT

Snipped
Speaking of terminology, can you remind me again what or whom exactly
is the/a *focal point* of database theory? And by whose logic does one
assign a spatial/relative location to a scientist into a scientific
universe of discourse ?
A question always comes back to my mind: Why do we always have to

Re: compound propositions

r...@raampje.lan (Reinier Post) — Fri, 19 mrt 2010 21:36:13 UT

I wholeheartedly agree with your position that ill-defined terms have
no place in formal argument. But requiring the use of someone else's
vocabulary, at considerable expense (127 Swiss Francs if I recall
correctly), without any indication that it will provide the formal rigor
required, takes us out of mathematics into the realm of sectarism.

Re: compound propositions

davi...@iinet.net.au (David BL) — Fri, 19 mrt 2010 07:39:06 UT

Indeed, and when I first came across the term "internal predicate" I
assumed it meant this (boolean valued) characteristic function of a
base or derived relvar of a given database.
I had no idea C.Date intended "internal predicate" to represent
integrity constraints on a relvar. It appears to be a predicate that

Re: compound propositions

bbad...@pei.sympatico.ca (Bob Badour) — Fri, 19 mrt 2010 02:41:26 UT

There is one thing that bothers me about the above definition of
"internal predicate". One could define a boolean function that returns
true for any argument tuples contained in a relation and false for all
other arguments. That function is arguably a characteristic function or
predicate and is represented internal to the formalism.

Re: compound propositions

toledobythe...@oohay.ac (paul c) — Fri, 19 mrt 2010 01:14:51 UT

Sorry for the drunken typo'. I meant pedantry.

Re: compound propositions

bbad...@pei.sympatico.ca (Bob Badour) — Thu, 18 mrt 2010 23:07:32 UT

I am not sure what you are asking. I agree one cannot teach genius, if
that's what you are getting at. Education is necessary not sufficient.

Re: compound propositions

toledobythe...@oohay.ac (paul c) — Thu, 18 mrt 2010 22:44:48 UT

...
Heh, now you're talking. (Still, he may have just bought passage and
left the rest to the principle all great convergers follow of preferring
to know as little as possible because knowing more would just get in the
way of finishing.)

Re: compound propositions

toledobythe...@oohay.ac (paul c) — Thu, 18 mrt 2010 22:40:12 UT

...
Alright I'll break what I said about no more comments today and my rule
about not posting after I've opened the cheap plonk - another of your
points seems to be that precision is required in order to recognize what
still needs to be defined, eg., 'what is outside of the box' as you put
it. But beyond some point or other (I suspect and hope you will

Re: compound propositions

bbad...@pei.sympatico.ca (Bob Badour) — Thu, 18 mrt 2010 22:39:23 UT

Now you are using "satisfy" to mean something entirely different yet again.
Neither headers nor relations satisfy predicates. A relation is the
extent of some predicate. The tuples of a relation are the instances
that satisfy the predicate. The header is a notational artefact of the
formalism.
How successful an explorer would Columbus have been had he not been able

Re: compound propositions

bbad...@pei.sympatico.ca (Bob Badour) — Thu, 18 mrt 2010 22:13:22 UT

All the terms I mentioned are fundamental. If I recall correctly, they
are all defined in 2382-01. Information and data are the first 2
definitions as I recall.
Not that I am aware of. Almost certainly not anything to do with
'relvar' because the standard vocabularies were mostly published before

Re: compound propositions

toledobythe...@oohay.ac (paul c) — Thu, 18 mrt 2010 22:10:12 UT

...
Maybe, if it is possible to talk theory without ever talking
implementation (which has its own conceptual, logical and physical
'levels'). Personally, if a relation has a header and the header
satisfies a predicate, I have no problem with the statement that a
relation satisfies a predicate, in the same way that if ISO/IEC

Re: compound propositions

toledobythe...@oohay.ac (paul c) — Thu, 18 mrt 2010 21:56:17 UT

Can't seem to find online the portion that this refers to (at least
without paying), maybe I'll have to find a library that has them all.
The ones I've seen aren't what I'd call formal, though they offer
examples and context that may be valuable for starting discussions if
nothing else.
Which sections or portions refer to 'internal' for example? Are

Re: compound propositions

bbad...@pei.sympatico.ca (Bob Badour) — Thu, 18 mrt 2010 21:55:26 UT

Which is what opens you to questions like David BL's and to criticisms
like mine.

Re: compound propositions

toledobythe...@oohay.ac (paul c) — Thu, 18 mrt 2010 21:21:16 UT

I didn't give a formal definition and didn't pretend to (my disclaimer
was snipped).