Some inequalities involving lower bounds of operators on weighted sequence spaces by a matrix norm


Dept. of Math.,University of Sistan and Baluchestan , Zahedan, Iran.


Let $A=(a_{n,k})_{n,k\geq1}$ and $B=(b_{n,k})_{n,k\geq1}$ 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 $0 < q \leq p \leq1$. Also for the case $p = 1$, we obtain $\|Ax\|_{v,B(1)}$, and for the case $p\geq 1$, we obtain $L_{v,p,q,B}(A)$.