Noninclusion theorems: some remarks on a paper by J. A. Fridy

Abstract

In 1997, J. A. Fridy gave conditions for noninclusion of ordinary and of absolute summability domains. In the present note, these conditions are interpreted in a natural topological context thus giving new proofs and also explaining why one of these conditions is too weak. Also an open question posed in Fridy's paper is answered.

Keywords

• Summability matrix
• summability domains inclusion
• absolute summability domains inclusion.