[01Y] Show instead that the axiom of infinity, and the consequent construction of the natural numbers seen in Sec. [246]↺↻, implies that there is a sequence \(x_ 1,\ldots x_ n,\ldots \) of sets for which \(x_ 1∈ x_ 2∈ x_ 3 \ldots \).
[01Z]↺↻
