# Re: cdt glossary [Graph] (was: what are keys and surrogates?)

From: David BL <davidbl_at_iinet.net.au>

Date: Sat, 12 Jan 2008 00:14:47 -0800 (PST)

Message-ID: <ba0fcb8d-b217-4c75-8381-2521adbb34f9_at_f47g2000hsd.googlegroups.com>

Date: Sat, 12 Jan 2008 00:14:47 -0800 (PST)

Message-ID: <ba0fcb8d-b217-4c75-8381-2521adbb34f9_at_f47g2000hsd.googlegroups.com>

On Jan 12, 2:24 pm, JOG <j..._at_cs.nott.ac.uk> wrote:

> On Jan 12, 1:05 am, David BL <davi..._at_iinet.net.au> wrote:

> > Really! I have seen a (mathematical) relation formally defined as a

*> > subset of a cartesian product (and not an ordered tuple) on many
**> > occasions.
**>
**> Bit confused by this - a cartesian product generates a set of ordered
**> tuples (over which a function is a subset), and all the hyperlinks you
**> listed seemed to follow that description.
*

Do you agree that most authors define a binary relation as a set of ordered pairs? In an earlier post you said a function is the ordered triple (D,C,G). How do you reconcile saying that a function is a (binary) relation? Received on Sat Jan 12 2008 - 09:14:47 CET