Tauberian theorems for Cesàro summable double sequences

This thesis consists of three chapters. In the fi rst chapter, briefly, summability methods and the historical developments of Tauber theory will be mentioned. For the single and double sequences, the studies done in the fields of Ces àro summability will be summarized. Also, there will be given information about the studies which will be done in the thesis. In the second chapter, there will be given information as a summary about the Ces àro summability of single sequences. And then, for the Ces àro summability of double sequences will be given basic de finition and notations, Tauber type theorem will be proved for (C,1,1) summability methods. In the third chapter, for single and double sequence, the concept of the regularly generated sequences will be given and then, by using the concept of the regularly generated sequence, Tauber type theorems will be proved for double sequences.