Quasi-equicontinuous sets of functions
Chien Wenjen
Abstract
Open-access reader
Chien Wenjen
Abstract
Open-access reader
The well-known theorem of analysis that if F is a family of functions defined, equicontinuous, and uniformly bounded on a bounded closed set E in n-dimensional real cartesian space Rn, then from every sequence {fn } of functions of F it is possible to select a uniformly convergent subsequence, has been recently generalized to various abstract spaces [1; 4; 6]. Consider a set F of continuous functions on one topological space X to another, Y. For any point x of X and any open set W of Y we denote by (x, W) the totality of functions f in F for which f(x) ? W. The topology in F obtained by employing all sets of the (x, W) as a subbase in F is called the p-topology by Arens [2]. The purpose of this note is to find the necessary and sufficient conditions that it be possible to select a subsequence converging pointwise to a continuous function from any given sequence of continuous functions and the necessary and sufficient conditions that a set of continuous functions be compact in the p-topology. DEFINITION. Let {fn } be a sequence of functions from a topological space X to be metric space Y. {fn } is said to be e-related at a point xCX if for every arbitrarily chosen e>0 there is a neighborhood U(x) of x such that, corresponding to each point x' U(x), a positive number N,(x, x') can be determined satisfying the condition:
OpenAlex reports 1 citations for this work. Citation counts describe recorded attention and do not establish research quality.
A contribution statement is not available in the OpenAlex record.
Method details are not available in the OpenAlex metadata.
Findings are not separately available in the OpenAlex metadata.
Limitations are not available in the OpenAlex metadata.
Application details are not available in the OpenAlex metadata.
The well-known theorem of analysis that if F is a family of functions defined, equicontinuous, and uniformly bounded on a bounded closed set E in n-dimensional real cartesian space Rn, then from every sequence {fn } of functions of F it is possible to select a uniformly convergent subsequence, has been recently generalized to various abstract spaces [1; 4; 6]. Consider a set F of continuous functions on one topological space X to another, Y. For any point x of X and any open set W of Y we denote by (x, W) the totality of functions f in F for which f(x) ? W. The topology in F obtained by employing all sets of the (x, W) as a subbase in F is called the p-topology by Arens [2]. The purpose of this note is to find the necessary and sufficient conditions that it be possible to select a subsequence converging pointwise to a continuous function from any given sequence of continuous functions and the necessary and sufficient conditions that a set of continuous functions be compact in the p-topology. DEFINITION. Let {fn } be a sequence of functions from a topological space X to be metric space Y. {fn } is said to be e-related at a point xCX if for every arbitrarily chosen e>0 there is a neighborhood U(x) of x such that, corresponding to each point x' U(x), a positive number N,(x, x') can be determined satisfying the condition:
Key concepts: Equicontinuity, Mathematics, Pointwise, Subsequence, Topology (electrical circuits), Bounded function, Sequence (biology), Uniform continuity