S.M.Kahrs S.M.Kahrs@ukc.ac.uk
Tue, 11 Dec 2001 10:20:39 +0000

The natural reading of 'greatest' is, of course,
the greatest in the divisibility preorder (it's partial order
on natural numbers but only a preorder on integers).
Thus, gcd 0 0 =3D 0.

3 and -3 are equivalent in that preoder.

Thus, an additional comment may be in order.