Re: c.d.theory glossary (repost)
From: Paul <paul_at_test.com>
Date: Fri, 14 May 2004 14:56:11 +0100
Message-ID: <Ud4pc.4185$NK4.362964_at_stones.force9.net>
>
> That's a mathematical def of domain, which is where Codd started. Again, a
> "b" definition might be in order -- what do you like as a def?
Date: Fri, 14 May 2004 14:56:11 +0100
Message-ID: <Ud4pc.4185$NK4.362964_at_stones.force9.net>
>>>[Domain] >>>Given a relation R, a domain is a set Sn such that for each tuple (A1, >>>A2, ...An, ...Am) in R, An is an element of Sn.
>
> That's a mathematical def of domain, which is where Codd started. Again, a
> "b" definition might be in order -- what do you like as a def?
--- Sometimes a "domain" is taken to include operators on the set, as well as the set of values itself. For example an integer domain might include addition and multiplication operators, and greater than / less than operators. I'm not sure about this last bit though because what about operators that take arguments from more than one domain? Or operators that return a value that isn't in the domain of the arguments? Where do they fit in? Paul.Received on Fri May 14 2004 - 15:56:11 CEST