Re: Example of expression bias?

paul c wrote:
> Tony D wrote:
> > ...
> >> A data type in RM = (a domain1 to draw values from) + (restrictions
> >> implemented on domain1 --> domain constraint) + (operators that can be
> >> defined using that data type)
> >> ...
> >
> > This may be one definition of a data type (not quite one I'd accept, as
> > we've thrashed over elsewhere), but there is nothing particular to RM
> > about this.
> > ...
>
>
> "domain constraint" seems an uncommon term to me because we usually talk
> of constraints on relations. but I often puzzle over constraints,
> thinking that they could be as fundamental as any other notion, e.g.,
> once one arrives at a similar conception of relations to Codd's, one
> could view everything that one does with them as either adding or
> subtracting constraints.
Interesting but no. domains is one of Codd's major achievements.

> p
Received on Wed Jun 21 2006 - 08:27:40 CEST