Davis-Kahan theorem
= Davis-Kahan theorem
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The Davis-Kahan theorem bounds the change of an invariant <eigenspace> of a <symmetric matrix> in terms of a matrix perturbation and an appropriate <spectral gap>. The <rank-one eigenprojector perturbation bound> below depends only on the unperturbed gap. https://arxiv.org/abs/1405.0680[Yu, Wang and Samworth's formulation] gives population-gap bounds in greater generality.