LIB "difform.lib";
ring R = 0,(x,y,z),ds;
diffAlgebra();
==> // The differential algebra Omega_R was constructed and the differential \
   forms dDx, dDy, dDz, dx, dy, dz are available.
/////////////////////////////////////////////////
// Applications of negated comparison operator //
/////////////////////////////////////////////////
difform df = 3*dx - x8*dx*dy;
difform dg = 3 + x8*dy;
df != dg;
==> 1
dg = dg*dx;
df != dg;
==> 0
kill Omega_R,df,dg,dx,dy,dz;