reserve n for non zero Nat,
  j,k,l,m for Nat,
  g,h,i for Integer;

theorem Th1:
  for m being Nat st m > 0 holds m * 2 >= m + 1
proof
  let m be Nat;
  assume m > 0;
  then
A1: m >= 0 + 1 by INT_1:7;
  m * 2 = m + m;
  hence thesis by A1,XREAL_1:6;
end;
