theorem Th6:
  x <> y & y <> z & z <> x implies v/(x,m1)/(y,m2)/(z,m3) = v/(z,m3
  )/(y,m2)/(x,m1) & v/(x,m1)/(y,m2)/(z,m3) = v/(y,m2)/(z,m3)/(x,m1)
proof
  assume that
A1: x <> y and
A2: y <> z and
A3: z <> x;
A4: v/(z,m3)/(y,m2) = v/(y,m2)/(z,m3) by A2,FUNCT_7:33;
  v/(x,m1)/(y,m2) = v/(y,m2)/(x,m1) by A1,FUNCT_7:33;
  hence thesis by A3,A4,FUNCT_7:33;
end;
