×

Some inequalities involving lower bounds of operators on weighted sequence spaces by a matrix norm. (English) Zbl 1281.26019

Summary: Let \(A = (a_{n,k})_{n,k\geq 1}\) and \(B = (b_{n,k})_{n,k\geq 1}\) be two non-negative matrices. Denote by \(L_{v,p,q,B}(A)\), the supremum of those \(L\), satisfying the following inequality:
\[ \|Ax\|_{v,B(q)}\geq L \| x\|_{v,B(p)}, \]
where \(x\geq 0\) and \(x\in l_p(v,B)\) and also \(v = (v_n)_{n=1}^\infty\) is an increasing, non-negative sequence of real numbers. In this paper, we obtain a Hardy-type formula for \(L_{v,p,q,B}(H_\mu)\), where \(H_\mu\) is the Hausdorff matrix and \(0 < q \leq p\leq 1\). Also for the case \(p = 1\), we obtain \(\|A\|_{w,B(1)}\), and for the case \(p\geq 1\), we obtain \(L_{w,B(p)}(A)\).

MSC:

26D15 Inequalities for sums, series and integrals
47A30 Norms (inequalities, more than one norm, etc.) of linear operators
40G05 Cesàro, Euler, Nörlund and Hausdorff methods
46A45 Sequence spaces (including Köthe sequence spaces)
54D55 Sequential spaces