JOURNAL OF INEQUALITIES AND APPLICATIONS, 2010 (SCI-Expanded)
The P-core of a double sequence has been defined and it is studied by many authors. In this paper, we have determined two permutations pi(1) and pi(2) on the set of natural numbers for which P-coreA(pi 1)(x) = P-coreA(pi 2)(x) for all x is an element of l(infinity)(2).