Re: Logical equivalence of simple and complex types under the relational model?
From: Neo <neo55592_at_hotmail.com>
Date: 30 Nov 2004 19:03:34 -0800
Message-ID: <4b45d3ad.0411301903.658bd206_at_posting.google.com>
Date: 30 Nov 2004 19:03:34 -0800
Message-ID: <4b45d3ad.0411301903.658bd206_at_posting.google.com>
> > What is a type?
>
> A type is a set of values supporting the same operations.
What is a value? Or what is not a value? Can a person be a value (ie a set of persons)? Can I have a type without any values (ie a NULL set)? What if one of the values in the set doesn't support the same operation (ie 0 with respect to division in the set of integers; or amputee john with respect to walking in the set of persons). Is it then just a set but not a type? TIA. Received on Wed Dec 01 2004 - 04:03:34 CET