Variations on strong lacunary quasi-Cauchy sequences
We introduce a new function space, namely the space of N-theta(alpha)(p)-ward continuous functions, which turns out to be a closed subspace of the space of continuous functions. A real valued function f defined on a subset A of R, the set of real numbers, is N-theta(alpha)(p)-ward continuous if it preserves N-theta(alpha)(p)-quasi-Cauchy sequences, that is, (f(x(n))) is an N-theta(alpha)(p)-quasi-Cauchy sequence whenever (x(n)) is N-theta(alpha)(p)-quasi-Cauchy sequence of points in A, where a sequence (x(k)) of points in R is called N-theta(alpha)(p)-quasi-Cauchy if lim(r ->infinity) 1/h(r)(alpha) Sigma(k is an element of lr) vertical bar Delta x(k)vertical bar(p) = 0, where Delta x(k) = x(k+1) - x(k) for each positive integer k, p is a constant positive integer, alpha is a constant in ]0,1], I-r = (k(r-1), k(r)] and theta = (k(r)) is a lacunary sequence, that is, an increasing sequence of positive integers such that k(0) not equal 0, and h(r) : k(r) - k(r-1) -> infinity. Some other function spaces are also investigated. (C) 2016 All rights reserved.