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Mathlib.Analysis.InnerProductSpace.Semisimple

Semisimple operators on inner product spaces #

This file is a place to gather results related to semisimplicity of linear operators on inner product spaces.

theorem LinearMap.IsSymmetric.orthogonalComplement_mem_invtSubmodule {𝕜 : Type u_1} {E : Type u_2} [RCLike 𝕜] [NormedAddCommGroup E] [InnerProductSpace 𝕜 E] {T : Module.End 𝕜 E} {p : Submodule 𝕜 E} (hT : LinearMap.IsSymmetric T) (hp : p T.invtSubmodule) :
p T.invtSubmodule

The orthogonal complement of an invariant submodule is invariant.

theorem LinearMap.IsSymmetric.isFinitelySemisimple {𝕜 : Type u_1} {E : Type u_2} [RCLike 𝕜] [NormedAddCommGroup E] [InnerProductSpace 𝕜 E] {T : Module.End 𝕜 E} (hT : LinearMap.IsSymmetric T) :
T.IsFinitelySemisimple

Symmetric operators are semisimple on finite-dimensional subspaces.