Re: The MySQL/PHP pair

"Lemming" <thiswillbounce_at_bumblbee.demon.co.uk> wrote in message news:n56oo0lo6303mvumnci93jhsbt4ba32c9k_at_4ax.com...
> On Fri, 05 Nov 2004 23:14:45 +0000, Paul <paul_at_test.com> wrote:
>
> >Dawn M. Wolthuis wrote:
> >>> You could say this. But then L is a "variable" (in the predicate
> >>> logic sense) and not a predicate. So when we translate over to
> >>> relations, L is atomic in the sense that the relational system
> >>> cannot look inside it - its inner workings are only visible to the
> >>> type system. This is because the relational system can only look
> >>> inside predicates.
> >>
> >> I don't care how it is implemented. As far as I'm concerned, a
> >> relation is a type, just as a bag is a type or a string, or name.
> >
> >I don't think this is an implementation thing though - it's more
> >fundamental than that. I think the system of predicates has to be
> >isomorphic to the system of relations and unless you preserve things
> >like atomicity this won't be the case.
> >
> >And I don't think relations are just another type - they are special
> >because they represent your basic logical framework. All the other types
> >are just tacked on afterwards to make life easier. Relations are the
> >logic and the other types are the things that the logic talks about.
> >
> >>> Maybe there is some system of basic logic where lists are
> >>> fundamental concepts but I'm not aware of it (and I'm not being
> >>> facetious here).
> >>
> >> English? OK, I did take grad level logic courses once upon a time and
> >> I do recognize that a formal system of logic is important for
> >> querying the data, for example. But I use lists in English
> >> propositions often. Think of lists as connected by ANDs just as
> >> separate columns are except that they share the same type. What's so
> >> difficult about that? I guess the variable length of the list is
> >> one thing that could cause difficulty, but since it doesn't cause any
> >> difficulty in the environment in which I work, I suspect that any
> >> theorectical difficulty has work-arounds in the practical world.
> >
> >Well if you google around you can find websites that approach logic from
> >a more philosophical that mathematical angle, using sentences in a
> >natural language. But they still basically parallel the mathematic
> >definitions.
> >
> >>> The second question is why not start with second order logic? Well,
> >>> its theory is a lot more complicated and you get stuff like
> >>> Godel's theorems biting you with things like unprovability and
> >>> incompleteness.
> >>
> >> So what? Mathematicians have put up with Godel's theorem for quite
> >> some time and we haven't thrown out the Real numbers along with
> >> various operators because of it.
> >
> >Good point. It is a bit unnerving to think that all you've got might be
> >built on sand though. Interesting as well to see I think it was Dan's
> >post about the practical difficulties he faced trying to build a system
> >with nested relations.
> >
> >>> Where I'm not totally clear is how much this has to do with
> >>> infinities and whether the fact that databases are finite makes a
> >>> difference, or whether their unboundedness is sufficient to cause
> >>> problems.
> >>
> >> I don't know either. I would like to get my brain around this so I
> >> understand the arguements for eliminating lists in our data models.
> >
> >Maybe there are two possible arguments:
> >1) simplicity, because we want to base it on standard first-order logic.
> >2) to avoid logical paradoxes or queries that return incorrect results
> >etc. I'd like to see some concrete examples of this though.
>
> 3) It works. Don't fix it.

I do believe that is what the IMS folks have been saying for years ;-)

> Seriously though, if you want to invent a new modelling paradigm, go
> right ahead, just don't call it Relational. Call it ... umm ... PICK.

How 'bout XML for short? --dawn

> Lemming
> --
> Curiosity *may* have killed Schrodinger's cat.
Received on Sat Nov 06 2004 - 02:06:18 CET