# Re: Character string relation and functional dependencies

Date: Mon, 10 Dec 2007 10:59:40 -0800 (PST)

Message-ID: <e0e52d62-c37f-4061-ab9d-3983a5ed31ca_at_s12g2000prg.googlegroups.com>

On Dec 8, 8:05 pm, "V.J. Kumar" <vjkm..._at_gmail.com> wrote:

*> Tegiri Nenashi <TegiriNena..._at_gmail.com> wrote innews:cd2ad8bd-78ca-433d-bc0f-3e7ef0c0fe2a_at_e6g2000prf.googlegroups.com:
**>
*

> > On Dec 6, 2:38 pm, Jonathan Leffler <jleff..._at_earthlink.net> wrote:

*> >> Tegiri Nenashi wrote:
**> >> > On Dec 6, 9:40 am, rp..._at_pcwin518.campus.tue.nl (rpost) wrote:
**> >> >> Another difference is that database tables are finite and
**> >> >> variable,
**>
**> >> > Oh, relations in database world are certainly not restricted by
**> >> > finite cardinality.
**>
**> >> I thought that computers are finite, so the relations containable in
**> >> them are too - even if damn large. There's a big difference between
**> >> very large and infinite.
**>
**> > This doesn't really matter. You can still reason about infinite
**> > relations
**>
**> You can do that with your brain...
**>
**> with finite resources available on you computer platform.
**>
**> but not with that. The computer is an intrinsically finite gadget.
**> Therefore, you'd better use the finite model apparatus to reason about
**> things like the impossibility of expessing transitive closure in the
**> relational algebra. A lot of stuff like the compactness theorem does
**> not work with finite models which makes infinite model proofs
**> inapplicable in the finite case.
*

However, if we start with the finite relation x=1, the we can fetch all the matching tuples from x=y by "the index lookup". Received on Mon Dec 10 2007 - 19:59:40 CET