“…where the constants c > 0 is independent of χ (see [39]). The above properties of the energy functional Π(χ), the bilinear form B(Ω γ , •, •), and the set K t allow one to establish the existence of a unique solution ξ t = (U t , u t , φ t ) ∈ K t for problem (6); see [34]. Symmetry and continuity of the bilinear form B(Ω γ , •, •) and the properties of the set K t provide the equivalence of problem (6) to the variational inequality…”