Çakan C.Altay B.Coskun H.2024-08-042024-08-0420091303-5010https://hdl.handle.net/11616/91414The famous Knopp Core of a single sequence was extended to the P-core of a double sequence by R.F. Patterson. Recently, the MR-core and ?-core of real bounded double sequences have been introduced and some inequalities analogues to those for Knoop's Core Theorem have been studied. The aim of this paper is to characterize a class of four-dimensional matrices, and so to obtain necessary and sufficient conditions for a new inequality related to the P- and ?-cores.eninfo:eu-repo/semantics/closedAccessCore theorems and matrix transformationsDouble sequencesInvariant meansArticle38151582-s2.0-70350164645Q3