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arXiv · 2012.08688

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

Ivan Feshchenko
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Abstract

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 for the orthogonal projection onto the sum is given. We also show that this condition is sharp (in a certain sense).

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Ivan Feshchenko. 2020-12-16. When is the sum of closed subspaces of a Hilbert space closed?. https://arxiv.org/abs/2012.08688

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