Row-finite summation method

A matrix summation method determined by a row-finite matrix, that is, a matrix in which each row has only finitely many non-zero entries. An important special case of a row-finite summation method is a triangular summation method.

For every regular matrix summation method for sequences (cf. Regular summation methods), a row-finite summation method that is equivalent and compatible (see Inclusion of summation methods; Compatibility of summation methods) with it on the set of all bounded sequences can be constructed (see [3]). However, there exist regular matrix summation methods for which there is no equivalent row-finite summation method on the set of all sequences (see [4] for an example).

References

[1]	G.H. Hardy, "Divergent series" , Clarendon Press (1949)
[2]	R.G. Cooke, "Infinite matrices and sequence spaces" , Macmillan (1950)
[3]	A.L. Brudno, "Summation of bounded sequences by matrices" Mat. Sb. , 16 (1945) pp. 191–247 (In Russian) (English abstract)
[4]	P. Erdös, G. Piranian, "Convergence fields of row-finite and row-infinite Toeplitz transformations" Proc. Amer. Math. Soc. , 1 (1950) pp. 397–401