EN
In [11] and [7], the concepts of σ-core and statistical core of a bounded number sequence x have been introduced and also some inequalities which are analogues of Knopp's core theorem have been proved. In this paper, we characterize the matrices of the class $(S ∩ m, V_{σ})_{reg}$ and determine necessary and sufficient conditions for a matrix A to satisfy σ-core(Ax) ⊆ st-core(x) for all x ∈ m.