theorem Th7:
  (ComplexFuncMult(A)).(f,g) = (ComplexFuncMult(A)).(g,f)
proof
  now
    let x be Element of A;
    thus ((ComplexFuncMult(A)).(f,g)).x = g.x * f.x by Th2
      .= ((ComplexFuncMult(A)).(g,f)).x by Th2;
  end;
  hence thesis by FUNCT_2:63;
end;
