Re: What to call this operator?
From: Mikito Harakiri <mikharakiri_nospaum_at_yahoo.com>
Date: 29 Jun 2005 11:08:48 -0700
Message-ID: <1120068528.597148.237170_at_g14g2000cwa.googlegroups.com>
Date: 29 Jun 2005 11:08:48 -0700
Message-ID: <1120068528.597148.237170_at_g14g2000cwa.googlegroups.com>
Jon Heggland wrote:
> As fundamental operators. Or to be more precise: projection is called
> <REMOVE>, specifies the attributes to remove instead of retain, and
> corresponds to the existential quantifier. I think D&D's <RENAME> could
> be dispensed with using Tropashko's technique, though.
Ah, yes, renaming A(x,y)->A(w,z) is a composition of join and projection
project_w,z( A(x,y) |><| (x=w) |><| (y=z) ) Received on Wed Jun 29 2005 - 20:08:48 CEST