Re: Do Data Models Need to built on a Mathematical Concept?
Date: 4 May 2003 15:58:44 -0700
Message-ID: <4b45d3ad.0305041458.14afcf9b_at_posting.google.com>
> A (binary) relation is a subset of a Cartesian product.
Yes, you are in synch with text books.
This is INCORRECT because it misses the fundamental form of a binary
relation.
Schaum's Outline explains binary relation as follows:
A = (b,c)
AxB = ((b,j), (b,k), (b,l), (c,j), (c,k), (c,l))
then (b,j), (b,k) ... are binary relations.
(b,j) is NOT a single binary relation.
(b,j) is composed of TWO binary relations.
They will have to rewrite the books and take back some diplomas or more likely they will keep the current inaccurate definitions which makes my experience on google all the more interesting :) Received on Mon May 05 2003 - 00:58:44 CEST