Go backward to Construction from Sets
Go up to Top
Go forward to Auxiliary Notions
Definition: N, the set of natural numbers
Proposition: N is the smallest set that satisfies the properties:
0 in N; forall x in N: x' in N; forall F: (F(0) /\ forall x in N: F(x) => F(x+1)) => forall x in N: F(x).
Third Peano law is a consequence of this proposition.