Cakan, CelalAltay, BilalCoskun, Huesamettin2024-08-042024-08-0420092651-477Xhttps://hdl.handle.net/11616/104734The 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 sigma-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 sigma-cores.eninfo:eu-repo/semantics/closedAccessDouble sequencesInvariant meansCore theorems and matrix transformationsArticle3815158WOS:000266800700005Q4