Abstract
In the paper, for all n∈ℕ, we describe the set ∑n of all real numbers α admitting a collection of projections P 1,...,P n on a Hilbert space H such that ∑k=1 n P k=α I (I is the identity operator on H) and study the problem to find all collections of this kind for a given α∈∑ n .
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Kruglyak, S.A., Rabanovich, V.I. & Samoilenko, Y.S. On Sums of Projections. Functional Analysis and Its Applications 36, 182–195 (2002). https://doi.org/10.1023/A:1020193804109
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DOI: https://doi.org/10.1023/A:1020193804109