English
Composition of two LinearIsometryEquiv's is itself a LinearIsometryEquiv, i.e., trans acts like composition of maps.
Русский
Композиция двух линейно-изометрических эквивалентов образует 또ой эквивалент, и операция trans действует как композиция отображений.
LaTeX
$$$ (e_1 \\trans e_2) \\text{ is a linear isometry equivalence and } (e_1 \\trans e_2) = \\text{ composition of } e_2 \\circ e_1 $$$
Lean4
/-- Composition of `LinearIsometryEquiv`s as a `LinearIsometryEquiv`. -/
def trans (e' : E₂ ≃ₛₗᵢ[σ₂₃] E₃) : E ≃ₛₗᵢ[σ₁₃] E₃ :=
⟨e.toLinearEquiv.trans e'.toLinearEquiv, fun _ => (e'.norm_map _).trans (e.norm_map _)⟩