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Proof of `Unit vectors far from a subspace of smaller dimension`

groundedproofs/Lax606786Proofs/Auerbach.lean · lax-606786

What this proof establishes

Assuming the claims on the left, the claim on the right holds — checked by the archive's pipeline. Proof code is not displayed here.

Read the Lean proof on GitLab

Description

A projection of norm at most dimWdim W onto WW has a unit vector of AA in its kernel.