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;
reserve f for Function of Segm n,Segm k;

theorem Th15:
  n=0 & k=0 implies f is onto "increasing
proof
  assume that
A1: n=0 and
A2: k=0;
  rng f = {} by A1;
  hence thesis by A1,A2,FUNCT_2:def 3;
end;
