例えば、無限シングルトンの元が問題だという批判 対して、>>713に示したように (引用開始) https://en.wikipedia.org/wiki/Axiom_of_infinity Axiom of infinity 4 = {0,1,2,3} = { {}, {{}}, { {}, {{}} }, { {}, {{}}, {{}, {{}}} } }. A consequence of this definition is that every natural number is equal to the set of all preceding natural numbers. The count of elements in each set, at the top level, is the same as the represented natural number, and the nesting depth of the most deeply nested empty set {}, including its nesting in the set that represents the number of which it is a part, is also equal to the natural number that the set represents. (引用終り)
