Re: How is this collection called?

"Mikito Harakiri" <mikharakiri_at_iahu.com> wrote in message news:<ZYgac.11$mR.60_at_news.oracle.com>...
> I actually had [binary labeled] tree in mind:-) Therefore, it looks like
> those axioms alone doesn't define structure uniquely. Or can anybody suggest
> an axiom that distinguish tree and stack? (On the other thought, expression
> tree is often implemented as stack, so maybe they are identical structures?)

I think the problem is you've not defined exactly what you mean by "binary aggregation operator". If you wanted to get completely generic you'd have to look at the theories of algebraic structures like groups, semi-groups, etc.

There's no reason why a "union" of bags or lists has to be defined in the usual way, it's just an arbitrary choice that fits in with our vague conceptual ideas about what a union is.

Paul. Received on Wed Mar 31 2004 - 10:06:09 CEST