reserve k, l, m, n, i, j for Nat,
  K, N for non empty Subset of NAT,
  Ke, Ne, Me for Subset of NAT,
  X,Y for set;

theorem Th12:
  N c= Segm n implies min* N <= n-1
proof
A1: min* N in N by NAT_1:def 1;
  assume N c= Segm n;
  hence thesis by A1,Th10;
end;
