Some remarks on linear functional differential inequalities of hyperbolic type

We prove that, for the validity of a certain theorem on differential inequalities for a linear functional differential equation of hyperbolic type {fx327-01} with a negative linear operator {fx327-02}, it is necessary that ℓ be an (a, c)-Volterra operator. __________ Translated from Ukrains'kyi Matematychnyi Zhurnal, Vol. 60, No. 2, pp. 283–292, February, 2008.