Is %i an integer? - Adding more facts to the database
Subject: Is %i an integer? - Adding more facts to the database
From: Stavros Macrakis
Date: Sun, 28 Jun 2009 19:36:06 -0400
On Sun, Jun 28, 2009 at 5:53 PM, Leo Butler <l.butler at ed.ac.uk> wrote:
> ...It seems to me that there is a convention and it is reasonable:
> if x is declared to be in a set, but not explicitly declared to be
> in a subset, then it is assumed not to be in the subset.
>
I think that would be a *terrible* convention and it conflicts with standard
mathematics: writing x ? *C** never* implies x ? *R *in mathematics.
> The only other convention would be to respond 'unknown'. This would
> require one to ask for clarification or handle each case (t/f).
>
Yes, when necessary, either ask or return a conditional.
> I think it would be more sensible to introduce, for each type, its
> negation. At the moment, we have this for even/odd and
> rational/irrational.
>
That would also be useful.
-s