Neha Patil (Editor)

Almost convergent sequence

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A bounded real sequence ( x n ) is said to be almost convergent to L if each Banach limit assigns the same value L to the sequence ( x n ) .

Lorentz proved that ( x n ) is almost convergent if and only if

lim p x n + + x n + p 1 p = L

uniformly in n .

The above limit can be rewritten in detail as

( ε > 0 ) ( p 0 ) ( p > p 0 ) ( n ) | x n + + x n + p 1 p L | < ε .

Almost convergence is studied in summability theory. It is an example of a summability method which cannot be represented as a matrix method.

References

Almost convergent sequence Wikipedia