Re: Stored fields ordered left to right

"Adrian Kubala" <adrian_at_sixfingeredman.net> wrote in message news:slrnbvu8jn.ano.adrian_at_sixfingeredman.net...
> Dawn M. Wolthuis <dwolt_at_tincat-group.com> schrieb:
> > Yes, you are absolutely right. In fact, the model I work with is more
of a
> > di-graph of data and instead of joins, it uses data trees (much like the
> > web). This is accomplished with functions as well. Instead of using
two
> > different concepts -- sets/relations combined with operators, the model
I
> > work with uses functions in both cases.
>
> Functions are one-way mappings. Many relationships in the world work
> both ways. It certainly seems useful to distinguish these two kinds of
> relationships, which relations + functions does but functions alone does
> not.

This must be another issue of definitions because there are no functions in mathematics that are not relations. Functions are a particular type of relation. Without looking up Codd's redefinition of a function, if he has one, but just sticking to pure mathematical definitions, a function is necessary a relation, so your statement could not possibly be true in that realm. In areas other than mathematics, I'm sure that people can redefine these concepts any way they wish.

But are we in agreement that using mathematics terminology and working from the standpoint of mathematics, all functions are, by definition, also relations? Thanks. --dawn Received on Sat Jan 10 2004 - 04:18:05 CET