Lower bounds for some factorable matrices

Lower Bounds for Some Factorable Matrices

The following conjecture was posed by Axler and Shields. Let {xn} be a monotone decreasing sequence of nonnegative numbers, C the Cesáro matrix of order one. What is the best constant K for which ‖Cx‖2 ≥ K‖x‖2 for all such sequences {xn}? Lyons [3] determined that the best constant is π/ √ 6. This result was extended to p spaces for p > 1 by Bennett [1]. In [1], Bennett established the followin...

Some Lower Bounds for Estrada Index

Some lower bounds for the $L$-intersection number of graphs

‎For a set of non-negative integers~$L$‎, ‎the $L$-intersection number of a graph is the smallest number~$l$ for which there is an assignment of subsets $A_v subseteq {1,dots‎, ‎l}$ to vertices $v$‎, ‎such that every two vertices $u,v$ are adjacent if and only if $|A_u cap A_v|in L$‎. ‎The bipartite $L$-intersection number is defined similarly when the conditions are considered only for the ver...

Lower bounds of Copson type for the transpose of matrices on weighted sequence spaces

The lower bounds for the rank of matrices and some sufficient conditions for nonsingular matrices

The paper mainly discusses the lower bounds for the rank of matrices and sufficient conditions for nonsingular matrices. We first present a new estimation for [Formula: see text] ([Formula: see text] is an eigenvalue of a matrix) by using the partitioned matrices. By using this estimation and inequality theory, the new and more accurate estimations for the lower bounds for the rank are deduced....