Quasi-Density of Sets, Quasi-Statistical Convergence and the Matrix Summability Method

In this paper, we define the quasi-density of subsets of the set of natural numbers and show several of the properties of this density. The quasi-density dp(A) of the set A⊆N is dependent on the sequence p=(pn). Different sequences (pn), for the same set A, will yield new and distinct densities. If the sequence (pn) does not differ from the sequence (n) in its order of magnitude, i.e., limn→∞pnn=1, then the resulting quasi-density is very close to the asymptotic density. The results for sequences that do not satisfy this condition are more interesting. In the next part, we deal with the necessary and sufficient conditions so that the quasi-statistical convergence will be equivalent to the matrix summability method for a special class of triangular matrices with real coefficients