Pringsheim Convergence and the Dirichlet Function

作     者：Thomas Beatty Bradley Hansen Thomas Beatty;Bradley Hansen

作者机构：Department of Mathematics Florida Gulf Coast University Ft. Myers FL USA 

出 版 物：《Advances in Pure Mathematics》 (理论数学进展（英文）)

年 卷 期：2016年第6卷第6期

页      面：441-445页

学科分类：07[理学] 0701[理学-数学] 070101[理学-基础数学] 

主　　题：Convergence Pointwise Limit Double Sequence Pringsheim Dirichlet Function Baire Category Theorem Cosine 

摘      要：Double sequences have some unexpected properties which derive from the possibility of commuting limit operations. For example, may be defined so that the iterated limits and exist and are equal for all x, and yet the Pringsheim limit does not exist. The sequence is a classic example used to show that the iterated limit of a double sequence of continuous functions may exist, but result in an everywhere discontinuous limit. We explore whether the limit of this sequence in the Pringsheim sense equals the iterated result and derive an interesting property of cosines as a byproduct.