“…Such quantities are called measures of weak non-compactness. Measures of non-compactness or weak noncompactness have been successfully applied to study of compactness, in operator theory, differential equations and integral equations, see for instance [2,3,5,6,7,8,9,10,12,13]. An axiomatic approach to measures of weak non-compactness may be found in [4,13].…”