FDs and confluence

[Ross Paterson]

On Thu, Apr 13, 2006 at 05:10:36PM -0700, Iavor Diatchki wrote:
> > > I understand the reduction steps.  Are you saying that the problem is
> > > that the two sets are not syntactically equal?   To me this does not
> > > seem important: we just end up with two different ways to say the same
> > > thing (i.e., they are logically equivalent).
> >
> > If c were mentioned in another constraint, they would not be equivalent.
> 
> How so?  A concrete example would really be useful.  I think that the
> constraint 'C [a] b d' and 'C [a] c d' are equivalent and I don't see
> how the rest of the context can affect this (of course I have been
> wrong in the past :-).

They are equivalent, but C [a] b d, Num c and C [a] c d, Num c are not.