(T T' : F →L[ℂ] F) (W : Submodule ℂ F) (k : ℕ) (hne : (minmaxSetIn T' W k).Nonempty) : minmaxLevel T k ≤ minmaxLevelIn T' W k + ‖T - T'‖

-- Generated from ChapterSirkRitzPerturbation.lean — theorem BookProof.RitzPerturbation.minmaxLevel_le_minmaxLevelIn_add
import Mathlib
import Definitions.Def_ChapterSirkRitzPerturbation
open BookProof.RitzPerturbation








noncomputable section


open BookProof.RitzMinMax BookProof.ChapterSirkRitzSpectrum BookProof.HermiteGalerkin
open Filter Topology

variable {F : Type*} [NormedAddCommGroup F] [InnerProductSpace ℂ F] [CompleteSpace F]

theorem BookProof.RitzPerturbation.minmaxLevel_le_minmaxLevelIn_add (T T' : F →L[ℂ] F) (W : Submodule ℂ F) (k : ℕ)
    (hne : (minmaxSetIn T' W k).Nonempty) :
    minmaxLevel T k ≤ minmaxLevelIn T' W k + ‖T - T'‖ := by sorry