Re: Notions of Type
From: paul c <toledobythesea_at_oohay.ac>
Date: Thu, 17 Aug 2006 23:59:32 GMT
Message-ID: <Ep7Fg.426352$IK3.188701_at_pd7tw1no>
>
> Except that union applies to relations of the same arity only.
Date: Thu, 17 Aug 2006 23:59:32 GMT
Message-ID: <Ep7Fg.426352$IK3.188701_at_pd7tw1no>
Aloha Kakuikanu wrote:
> Keith H Duggar wrote:
>> Marshall wrote: >>> Very true. Of the various relational operators that have >>> been identified over the years, only a few, like union, >>> are really algebraic.
>
> Except that union applies to relations of the same arity only.
I thought that was only a practical restriction, ie., in theory, any relations can be unioned?
p Received on Fri Aug 18 2006 - 01:59:32 CEST