Let R be a ring. A right R-module M with S = End(MR) is called a quasi AP-injective module, if, for any s ∈ S, there exists a left ideal Xs of S such that lS(k
In this paper we introduce two sequences of operator functions and their dual functions: fk(t) = (tlogt)k-(t-1)k/logk+1 t (k = 1,2,…), gk(t) = (t-1)k-logkt/log