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Kyungpook Mathematical Journal 2019; 59(1): 47-63

Published online March 23, 2019

Copyright © Kyungpook Mathematical Journal.

A Note on Spliced Sequences and A-density of Points with respect to a Non-negative Matrix

Kumardipta Bose*, and Sayan Sengupta

Department of Mathematics, Jadavpur University, Kolkata 700032, India
e-mail: gabuaktafaltu6ele@hotmail.com and mathematics.sayan1729@gmail.com

Received: October 12, 2017; Revised: October 3, 2018; Accepted: October 10, 2018

Abstract

For y ∈ ℝ, a sequence x = (xn) ∈ ℓ, and a non-negative regular matrix A, Bartoszewicz et. al., in 2015, defined the notion of the A-density δA(y) of the indices of those xn that are close to y. Their main result states that if the set of limit points of (xn) is countable and density δA(y) exists for any y ∈ ℝ where A is a non-negative regular matrix, then limn→∞(Ax)n = ∑y∈ℝδA(y) · y. In this note we first show that the result can be extended to a more general class of matrices and then consider a conjecture which naturally arises from our investigations.

Keywords: non-negative matrix, A-density, A-limit,ideal convergence, in nite splice, conjecture (*).