“…We recall that the map (v, T ) → (ρ Γ , S Γ ), where Γ is the Gibbs state of (v, T ), is injective, this is the Hohenberg-Kohn theorem for systems at positive temperature, see [18] and [4,Theorem 4.1], and this exposes the (v, T ) − (ρ, S) duality. The information of the internal quantities (ρ, S) enables to recover the information of the external fields (v, T ).…”