I. Feshchenko

activity

20082020

most citedRealization of the Werner-Holevo and Landau-Streater quantum channels for qutrits on quantum computers

5 citations · 8 across the 12 of their papers we have counts for

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Showing 2020Show all

2 papers · 1 filter

math.FA2020★ 2 cited

When is the sum of closed subspaces of a Hilbert space closed?

Ivan Feshchenko

We provide a sufficient condition for a finite number of closed subspaces of a Hilbert space to be linearly independent and their sum to be closed. Under this condition a formula f…

math.FA2020

On the inverse best approximation property of systems of subspaces of a Hilbert space

Ivan Feshchenko

Let $H$ be a Hilbert space and $H_{1}, ..., H_{n}$ be closed subspaces of $H$ . Denote by $P_{k}$ the orthogonal projection onto $H_{k}$ , $k = 1, 2, ..., n$ . Following Patrick L. Combettes and Nol…