Qed.

Lemma WeakR : forall Γ Δ1 Δ2 A, Γ ⊃ Δ1++Δ2 -> Γ ⊃ Δ1++A::Δ2.
intros;remember (Δ1++Δ2);revert Δ1 Δ2 Heql;temp3 H IHG IHG1 IHG2 Heql A0.