a Faculty of Physics, Yerevan State University, Alex Manoogian street 1, Yerevan 375025, Armenia b Fakultet Organizacionih Nauka, Jove Ili?a 154, Belgrade, Serbia c Matemati?ki Fakultet, Studentski trg 16, 11001 Belgrade, p.p. 550, Serbia
Abstract:
It is proved that the inequality δX(ε)?cεp, p?2, where δX is the modulus of convexity of X, is sufficient and necessary for the inequality