reserve r, s, t, g for Real,

          r3, r1, r2, q3, p3 for Real;
reserve T for TopStruct,
  f for RealMap of T;

theorem Th9:
  f is continuous implies -f is continuous
proof
  assume
A1: f is continuous;
  let X be Subset of REAL;
  assume X is closed;
  then
A2: --X is closed by MEASURE6:45;
  (-f)"X = f"(--X) by MEASURE6:68;
  hence thesis by A1,A2;
end;
