Set

A set is a collection of objects. For example, one can define the set '''S''' = {Sn: Sn is a sibling of the Larry M. Sanger, who is the Editor-in-Chief of Nupedia}.

We require that sets be well-defined. Given an object Sn, we must be able to determine if Sn belongs to '''S'''.---- 

'''What, there are no recursively enumerable sets?'''
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Mathematicians are prone to present sets of numbers as examples:
#[[Natural Numbers]] which are used for counting the members of sets.
#[[Integers]] which appear as solutions to equations like x+a=b.
#[[Rational Numbers]] which appear as solutions to equations like a+bx=c.
#[[Algebraic Numbers]] which can appear as solutions to polynomial equations (with rational coefficients) and may involve [[radical]]s.
#[[Real Numbers]] which include [[Transcendental Numbers]] (which can't appear as solutions to polynomial equations with rational coefficents) as well as the [[Algebraic Numbers]]

[[Statistical Theory]] is built on the base of [[Set Theory]] and [[Probabillity Theory]].