enrich
nat
with
functions min : nat × nat → nat;
max : nat × nat → nat;
axioms min : ⊦ min(n, m) = (n < m ⊃ n;m);
used for: s, ls;
max : ⊦ max(n, m) = (n < m ⊃ m;n);
used for: s, ls;
end enrich