Re: Relation Schemata vs. Relation Variables

From: vc <boston103_at_hotmail.com>
Date: 6 Sep 2006 06:04:45 -0700
Message-ID: <1157547885.679828.23080@h48g2000cwc.googlegroups.com>

Jan Hidders wrote:
[...]

>. Note btw. that they are a strict

> subclass of the restrictions that might be expressed by some kind of
> temporal logic.

What temporal logic do you have in mind ? It's known that first-order temporal logic is strictly less expressive than FOL for a relational database augmented in a natural way with a timestamp column, or in other words FOTL is less expressive than two sorted FOL with the time domain as an additional sort ( the propositional fragments of both are equivalent).

> -- Jan Hidders
Received on Wed Sep 06 2006 - 08:04:45 CDT