[r6rs-discuss] Re: Plausible list problems

From: AndrevanTonder <andre>
Date: Wed Oct 4 07:24:43 2006

On Tue, 3 Oct 2006, William D Clinger wrote:

> I can only repeat that, although plausible list-ness is
> undecidable, the quoted wording says exactly the right
> thing, albeit in language that should be made clearer
> for the non-logicians among us: Implementations are
> required to confirm (i.e. prove) that the alleged list
> argument is a plausible list, and must raise an exception
> if that confirmation (i.e. attempted proof) fails.
>
> That the implementation's attempt to confirm can fail
> even when the argument really is a plausible list is
> clear to both of us, since you and I agree that the
> question is undecidable.

No, this last sentence is not clear to me, and in fact
exactly what bothers me.

An undecidable question cannot be proved false in a sound
proof system, so are you allowing unsound proofs, and if so,
which ones?

Cheers
Andre
Received on Wed Oct 04 2006 - 07:21:53 UTC