Re: Transitive Closure
From: x <x-false_at_yahoo.com>
Date: Tue, 18 May 2004 14:48:14 +0300
Message-ID: <40a9f72d$1_at_post.usenet.com>
Date: Tue, 18 May 2004 14:48:14 +0300
Message-ID: <40a9f72d$1_at_post.usenet.com>
"Alfredo Novoa" <alfredo_at_ncs.es> wrote in message
news:e4330f45.0405180244.9d5d351_at_posting.google.com...
> mikharakiri_nospaum_at_yahoo.com (Mikito Harakiri) wrote in message
news:<8a529bb.0405171058.36a5a26_at_posting.google.com>...
>
> > So we are talking about different algebra, that has a universe with
> > elements being unary relational algebra operators only -- selection,
> > projection,
>
> They ARE binary operators. Restriction has two operands: a relation
> and a boolean function, and projection a relation and a set of
> attributes.
I think "they are" is too strong. I'd suggest "they may be regarded as".
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
- Usenet.com - The #1 Usenet Newsgroup Service on The Planet! *** http://www.usenet.com Unlimited Download - 19 Seperate Servers - 90,000 groups - Uncensored -=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=