Re: More on lists and sets
From: Marshall Spight <marshall.spight_at_gmail.com>
Date: 26 Mar 2006 18:36:56 -0800
Message-ID: <1143427016.770407.202720_at_i40g2000cwc.googlegroups.com>
Date: 26 Mar 2006 18:36:56 -0800
Message-ID: <1143427016.770407.202720_at_i40g2000cwc.googlegroups.com>
Mikito Harakiri wrote:
>
> Formal definition. Let A(x) and B(x) be lists. Convert them to
> relations
> A(x,y) and B(x,z) where attributes y and z are orderings.
That's very interesting. You've selected the name of the position attribute at the time of ordering. I hadn't considered that before.
> > As join/intersection is noncommutative, we have left selection and right
> selection.
I don't see why it's not commutative.
Marshall Received on Mon Mar 27 2006 - 04:36:56 CEST