There are no sets at all in first-order Peano arithmetic—sets are simply not a thing that the theory talks about.
(People talking about first-order Peano arithmetic, however, do talk about sets a lot.)
There are no sets at all in first-order Peano arithmetic—sets are simply not a thing that the theory talks about.
(People talking about first-order Peano arithmetic, however, do talk about sets a lot.)