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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_at_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 - 15:04:45 CEST












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