Re: Logical equivalence of simple and complex types under the relational model?

From: Alfredo Novoa <anovoa_at_ncs.es>
Date: Thu, 02 Dec 2004 01:56:38 +0100
Message-ID: <00qsq0di7qu5i25gceuib1hmikcqqmat60@4ax.com>

On Wed, 1 Dec 2004 16:37:31 +0100, "Rene de Visser" <Rene_de_Visser_at_hotmail.de> wrote:

>There is a type 'number' which includes all numbers.
>
>There are also types that subtypes of this type. For examples Integer.
>
>The total numerical tower is quite complicated.

I am not familiar with Common Lisp. Might be a value a member of several types with Common Lisp?

>> What is the ultimate type, or least the one that would include data types?
>
>I think this is likely to be type system specific, and that in a lot of type
>systems that there is no ultimate type.
>
>In common lisp the ultimate type is 't' (short for true) which all values
>are a members of.

This is very similar to Tutorial D in which all scalar values are members of Alpha, and none is member of Omega.

Regards Received on Wed Dec 01 2004 - 18:56:38 CST