[1] **viXra:0909.0039 [pdf]**
*submitted on 16 Sep 2009*

**Authors:** Victor Porton

**Comments:** 2 Pages.

In the framework of ZF formally considered generalizations, such as whole numbers generalizing
natural number, rational numbers generalizing whole numbers, real numbers generalizing
rational numbers, complex numbers generalizing real numbers, etc. The formal consideration
of this may be especially useful for computer proof assistants.

**Category:** Set Theory and Logic