Regular methods of summability and the Banach-Saks property for double sequences


Raluca Dumitru, Jose A Franco, Richard F Patterson




A Banach space B is said to satisfy the Banach-Saks property with respect to a regular summability method if every bounded subsequence has a summable subsequence. We show that if a Banach space satisfies the Banach-Saks property with respect to a Robison-Hamilton regular summability method, for every bounded double sequence there exists a β-subsequence whose subsequences are all summable to the same limit.