A note on Saleh ’ s paper ‘ Almost continuity implies closure continuity ’ ∗
نویسنده
چکیده
The first two implications are trivial. In [2], the second author showed that every almost α-continuous function is η-continuous. In [1], Dickman, Porter and Rubin proved that every η-continuous is θ-continuous and hence weakly continuous. Although θ-continuous functions behave, in general, nicely, they may cause some unexpected problems. For example, if f :X → Y is θ-continuous, then f :X → f(X) is not necessarily θ-continuous. Also, the set of all points of continuity of f :X → Y may be dense in X and f may not be weakly continuous in either of those points. We show that with the following example: Example. Consider the classical Dirichlet function f : (R, τd) → (R, τd), where R is the real line with the density topology τd:
منابع مشابه
On Fuzzy $e$-open Sets, Fuzzy $e$-continuity and Fuzzy $e$-compactness in Intuitionistic Fuzzy Topological Spaces
The purpose of this paper is to introduce and study the concepts of fuzzy $e$-open set, fuzzy $e$-continuity and fuzzy $e$-compactness in intuitionistic fuzzy topological spaces. After giving the fundamental concepts of intuitionistic fuzzy sets and intuitionistic fuzzy topological spaces, we present intuitionistic fuzzy $e$-open sets and intuitionistic fuzzy $e$-continuity and other results re...
متن کاملSome Remarks on Controllability of Evolution Equations in Banach Spaces
In almost all papers in the literature, the results on exact controllability hold only for finite dimensional Banach spaces, since compactness of the semigroup and the bounded invertibility of an operator implies finite dimensional. In this note we show that the existence theory on controllability in the literature, can trivially be adjusted to include the infinite dimensional space setting, if...
متن کاملSOME RESULTS OF CONTINUITY ?f
The dynamical behavior of a map on the unit interval has been the subject of much contemporary research. In this paper, we will consider the relation between the continuity of the map cof and cof for some positive integer k, where f is a continuous map from the unit interval to itself, and ?f is a function which takes any element of the unit interval to the set of all subsequential limits o...
متن کاملA Note on Generalized Topology
In this paper we deal with a concrete example of a generalized topological space and we shall examine some topological properties such as, the usual continuity, the net-continuity and the net-closure property for it. We will show that a generalized topological space has net-continuous property or net-closure property if and only if it is a topological space. Finally we give examples of continuo...
متن کاملA note on almost contra-precontinuous functions
Almost contra-precontinuous functions were introduced by Ekici [7] and recently have been investigated further by Noiri and Popa [13]. The purpose of this note is to develop some new characterizations of almost contra-precontinuous functions and to introduce a new weak form of almost contra-precontinuity, which we call subalmost contraprecontinuity. It is shown that subalmost contra-precontinui...
متن کامل