The Lean 4 theorem `preim_eq` in the `ChapterHashimotoShiftInvert` chapter of the timepiece formalization

-- Generated from ChapterHashimotoShiftInvert.lean — theorem BookProof.HashimotoShiftInvert.preim_eq
import Definitions.Def_ChapterFarisLavine
import Definitions.Def_ChapterYangMillsFriedrichs
import Definitions.Def_ChapterYangMillsFriedrichsLimit
import Definitions.Def_ChapterHermiteGalerkinFriedrichs
import Mathlib
import Definitions.Def_ChapterHashimotoShiftInvert
import Definitions.Def_ChapterComplexShiftCore
open BookProof.HashimotoShiftInvert

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



open BookProof.FarisLavine BookProof.YangMillsFriedrichs BookProof.YangMillsFriedrichsLimit
open BookProof.HermiteGalerkin
open Filter Topology

theorem BookProof.HashimotoShiftInvert.preim_eq (R : F →L[ℂ] F) (hinj : Function.Injective R)
    (y : LinearMap.range (R : F →ₗ[ℂ] F)) {u : F} (hu : R u = (y : F)) : preim R y = u := by sorry