Re: On Formal IS-A definition

On May 9, 11:38 am, Bob Badour <bbad..._at_pei.sympatico.ca> wrote:

> My set of three variables and a dog fully complies with ZFC.

Here is a quote from (http://en.wikipedia.org/wiki/Zermelo %E2%80%93Fraenkel_set_theory)

"ZFC has a single primitive ontological notion, that of a hereditary well-founded set, and a single ontological assumption, namely that all individuals in the universe of discourse are such sets. Thus, ZFC is a set theory without urelements (elements of sets which are not themselves sets)."

and this (from http://en.wikipedia.org/wiki/Hereditary_set)

"In set theory, a hereditary set (or pure set) is a set all of whose elements are hereditary sets. That is, all elements of the set are themselves sets, as are all elements of the elements, and so on."

I wonder whether Bob enjoys putting a leash on a set and taking it for a walk. Received on Sun May 09 2010 - 15:29:12 CEST