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The sequence spaces ℓp(Cn)$$ {\ell}_p\left({C}^n\right) $$, c0(Cn)$$ {c}_0\left({C}^n\right) $$ and c(Cn)$$ c\left({C}^n\right) $$ are introduced by Roopaei and Başar [8] as the domain of the Cesàro matrix Cn$$ {C}^n $$ of order n$$ n $$ in the spaces ℓp$$ {\ell}_p $$, c0$$ {c}_0 $$ and c$$ c $$ of absolutely p$$ p $$‐summable, null and convergent sequences, respectively, where 0

In this paper a multiplier theorem in the Hardy space H^1(\mathbb {T}) associated with Jacobi expansions of exponential type is proved, that is, a bilateral sequence \left \{\lambda _n\right \}_{n=-\infty }^{\infty } is a multiplier from H^1(\mathbb {T}) into the sequence space \ell ^1(\mathbb {Z}) associated with Jacobi expansions of exponential type, if \[ \sup _N\sum _{k=1}^{\infty }\left (\sum _{kN<|j|\le (k+1)N}|\lambda _j|\right)^2<\infty.\] This is a generalization of a multiplier theorem on usual Fourier expansions in the Hardy space H^1(\mathbb {T}), and for \lambda _n=(|n|+1)^{-1}, a Hardy type inequality for Jacobi expansions is immediate which has ever been proved by Kanjin and Sato [Math. Inequal. Appl. 7 (2004), pp. 551–555]. [ABSTRACT FROM AUTHOR]

Quite recently, we have obtained two main theorems dealing with absolute weighted arithmetic mean summability factors of infinite series and trigonometric Fourier series [C. R. Math. Acad. Sci. Paris 359 (2021), pp. 323–328]. In this paper, we have generalized these theorems for a general summability method. We have also obtained some new and known results for certain absolute summability methods. [ABSTRACT FROM AUTHOR]

The concept of Tribonacci sequence spaces by the domain of a regular Tribonacci matrix was introduced by Yaying and Hazarika (Math. Slovaca 70(3):697–706, 2000). In this paper, by using the domain of regular Tribonacci matrix T = (t i k) and the concept of neutrosophic convergence, we introduce some neutrosophic normed space in Tribonacci convergent spaces and prove some topological and algebraic properties based results with respect to these spaces. [ABSTRACT FROM AUTHOR]

In this note we introduce a new technique to answer an issue posed in Fávaro et al. (Bull Braz Math Soc 51:27–46, 2020) concerning geometric properties of the set of non-surjective linear operators. We also extend and improve a related result from the same paper. [ABSTRACT FROM AUTHOR]

In [Anal. Math. Phys., 8 (2018), 77-83], we have obtained two main theorems dealing with the | N ¯ , p n | k summability factors of infinite series and trigonometric Fourier series. In this paper, we have generalized these theorems for the | N ¯ , p n ; θ n | k summability methods. We have also obtained some new and known results for certain absolute summability methods. [ABSTRACT FROM AUTHOR]