“…If (M, F) = (R N , F) is a Minkowski space, the constant 4 (N −2) 2 is optimal, but no minimizers exist; see Van Schaftingen [9]. Note further that Hardy-type inequalities on Riemannian manifolds (M, F) = (M, g) have been studied in the papers of Carron [3], and Kombe and Özaydin [4]. for all u ∈ C ∞ 0 (M).…”