Ultra Bessel sequences in direct sums of Hilbert spaces

Authors

  • A. Rahimi University of Maragheh
  • M. R. Abdollahpour University of Mohaghegh Ardabili
Abstract:

In this paper, we establish some new results in ultra Bessel sequences and ultra Bessel sequences of subspaces. Also, we investigate ultra Bessel sequences in direct sums of Hilbert spaces. Specially, we show that {( fi, gi)}∞ i=1 is a an ultra Bessel sequence for Hilbert space H ⊕ K if and only if { fi}∞ i=1 and {gi}∞ i=1 are ultra Bessel sequences for Hilbert spaces H and K, respectively.

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Journal title

volume 2  issue 1

pages  55- 64

publication date 2015-09-01

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