Naive set theory：任给一个性质，满足该性质的所有集合总可以组成一个集合
Russell's paradox：当性质为x不属于x（x不是自身的元素）时产生
Axiomatic set theory：ZFC / NGB
Cantor's theorem：the cardinality (numerical size) of a set is strictly less than the cardinality of its power set (the set of all subsets)
Reference