Re: what are keys and surrogates?

On Jan 11, 1:11 pm, Keith H Duggar <dug..._at_alum.mit.edu> wrote:
> David BL wrote:
> > Marshall wrote:
> > > An interesting note, by the way: functions are relations...
>
> > Isn't it more precise to say that the graph of a function is a
> > relation?
>
> No, it isn't.
>
> http://mathworld.wolfram.com/Function.html

From mathworld a relation

    http://mathworld.wolfram.com/Relation.html

is defined as a subset of a cartesian product. If a function is a relation why do they define a graph of a function f as

    { (x,f(x)) | x in domain of f },

as described in

    http://mathworld.wolfram.com/FunctionGraph.html Received on Fri Jan 11 2008 - 06:28:10 CET