


Paper's Title:
Uniform Continuity and kConvexity
Author(s):
Adel Afif Abdelkarim
Mathematics Department, Faculty of Science,
J
erash University, Jerash
Jordan.
Abstract:
A closed arcwiseconnected subset A of R^{n} is called kconvex if for each positive number a and for all elements x and y in A there is a positive number b such that if the norm of xy is less than or equal to b then the length of the shortest curve l(x,y) in A is less than k times the norm of xy plus a. We show that a union of two non disjoint closed finite convex subsets need not be kconvex. Let f(x) be a uniformly continuous functions on a finite number of closed subsets A_{1},...,A_{n} of R^{n} such that the union of A_{j},...,A_{n},j=1,...,n1 is kconvex. We show that f is uniformly continuous on the union of the sets A_{i},i=1,...,n. We give counter examples if this condition is not satisfied. As a corollary we show that if f(x) is uniformly continuous on each of two closed convex sets A,B then f(x) is uniformly continuous on the union of A and B.
Paper's Title:
On a Problem on Periodic Functions
Author(s):
Adel A. Abdelkarim
Mathematics Department, Faculty of
Science,
Jerash Private University, Jerash,
Jordan.
Email:
adelafifo_afifo@yahoo.com
Abstract:
Given a continuous periodic real function f with n translates f_{1 },..., f_{n} , where f_{i}(x)=f(x+a_{i}), i=1,...,n. We solve a problem by Erdos and Chang and show that there are rational numbers r,s such that f(r)≥ f_{i}(r), f(s)≤ f_{i}(s), i=1,...,n. No restrictions on the constants or any further restriction on the function f are necessary as was imposed earlier.
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