Definition alphas_p : R -> R := d2 alphas.

Lemma D_Rs_2 : forall t : R, (derive_pt Rs t (Rs_derivable t) * (2 * derive_pt alphas t (cond_D1 alphas t) - derive_pt thetat t (thetat_derivable t)))%R = (- Rs t * derive_pt (derive alphas (cond_D1 alphas)) t (cond_D2 alphas t))%R.