# Proving $d(dx)=d^2x$

Is it possible to carry out the following differential in Mathematica?

$$d(dx) = d^2x$$

I tried to write:

Dt[1*Dt[x]]


the result is:

Dt[Dt[x]]


• For exterior derivatives $d(df)=0$ is the defining property. – yarchik Jan 5 '18 at 10:01