On the characterization of a class of four dimensional matrices and Steinhaus type theorems

In the present paper, we give the definitions of four dimensional conull and coregular matrices, and characterize the classes (Mu : Cυ), where υ _ {p, p0, ƒ} and Cƒ denotes the space of all almost convergent double sequences. Additionally, we give two Steinhaus type theorems related to the coercive/almost coercive four dimensional sequence to sequence matrix transformations.