Filomat, cilt.29, sa.9, ss.2107-2118, 2015 (SCI-Expanded, Scopus)
In this paper, we define the superposition operator Pg where g : N2 * R → R by Pg ((xks)) =g (k; s; xks) for all real double sequence (xks). Chew & Lee [4] and Petranuarat & Kemprasit [7] have characterized Pg : lp → l1 and Pg : lp → lq where 1 ≤ p; q < ∞, respectively. The main goal of this paper is to construct the necessary and sucient conditions for the continuity of Pg : Lp → L1 and Pg : Lp → Lq where 1 _ p; q < ∞.