Miller, Hugh wrote:

From: Moritz Lenz [mailto:[EMAIL PROTECTED][EMAIL PROTECTED] wrote:Technically the Cartesian cross operator doesn't have anidentity value. It has. The set which contains only the emty set, or in perl terms ([]); Or am I missing something?Should be a (any) 1 point set for the identity. How about considering models from category theory, rather than set theory ? Seems much more fruitful for computer issues than set theory.

`No an identity would be a set E such that for any set A: A x E = A, but`

`no such set exists. A singleton set get close, but the result is only`

`isomorphic (there is a natural bijection) not equal. Even in category`

`theory you only get isomorphism.`

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