
theorem
  for n being odd Nat st n<=8 holds n=1 or n=3 or n=5 or n=7
proof
  let n be odd Nat such that
A1: n<=8;
  n<>2*4;
  then n<7+1 by A1,XXREAL_0:1;
  then
A2: n<=7 by NAT_1:13;
  per cases by A2,XXREAL_0:1;
  suppose
    n=7;
    hence thesis;
  end;
  suppose
    n<6+1;
    then n<=6 by NAT_1:13;
    hence thesis by Th8;
  end;
end;
