Re: Does Codd's view of a relational database differ from that ofDate&Darwin?[M.Gittens]
Date: Mon, 04 Jul 2005 20:13:10 GMT
Jon Heggland wrote:
> In article <NBAxe.135734$rx6.7273595_at_phobos.telenet-ops.be>,
> jan.hidders_at_REMOVETHIS.pandora.be says...
>>>>Not really, I'm restricting it slightly. I'm using the one that says >>>>that a value is something that (1) has one or more representations, >>>>i.e., can be encoded in memory and (2) is identified by that encoding in >>>>the sense that some equivalence relation over all possible >>>>representations is defined and each value corresponds to an equivalence >>>>class defined by it. >>> >>>This sounds just like D&D's definition in TTM. But a lexical object is >>>not a value, it is the representation of a value? What then is a lexical >>>object *type*? >> >>A set of values.
> Let me try to sum up.
> A value has one or more representations.
Yes, but note that that was true in *my* definition of value. In ORM terminology the notions of value and representation are usually considered synonymous.
Again, under my definition of value. In ORM's vocabulary this would not be true.
Yep, although it would probably have been less confusing if I would have said it was a set of representations. My apologies for that.
- Jan Hidders