Re: Proposal: 6NF

From: Marshall <marshall.spight_at_gmail.com>
Date: 15 Oct 2006 12:02:53 -0700
Message-ID: <1160938972.963300.179450@b28g2000cwb.googlegroups.com>

On Oct 15, 7:39 am, "Jan Hidders" <hidd..._at_gmail.com> wrote:
>
> Note that Liskov and Wong themselves defined the principle
> as:
>
> Let q(x) be a property provable about objects x of type T. Then q(y)
> should be true for objects y of type S where S is a subtype of T.

Um, I'm on shaky ground here, but it seems to me that given Rice's theorem, you're not going to be able to use the above to prove a subtyping relationship; only disprove it. Am I way off?

Marshall Received on Sun Oct 15 2006 - 14:02:53 CDT