Some new subspaces of an FK-space and defferred Cesàro conullity

In this paper, we construct new important subspaces Dqp S, Dqp W, Dqp F and Dqp B for a locally convex FK-space X containing ϕ, the space of finite sequences. Then, we show that there is a relation among these subspaces. Also, we study deferred Cesàro conullity of one FK-space with respect to another, and we give some important results. Finally, we examine the deferred Cesàro conullity of the absolute summability domain lA, and show that if lA is deferred Cesàro conull, then A cannot be l-replaceable