English
A simp lemma stating symmetry of reindex in the dependent/unstated case.
Русский
Упрощенное леммное утверждение симметрии переиндексации в зависимом/неназначенном случае.
LaTeX
$$$@[simp] \\text{ reindex refl symmetric }$$$
Lean4
@[simp]
theorem reindex_refl : reindex R s (Equiv.refl ι) = LinearEquiv.refl R _ :=
by
apply LinearEquiv.toLinearMap_injective
ext
simp only [Equiv.refl_symm, Equiv.refl_apply, reindex, domDomCongrLinearEquiv', LinearEquiv.coe_symm_mk,
LinearMap.compMultilinearMap_apply, LinearEquiv.coe_coe, LinearEquiv.refl_toLinearMap, LinearMap.id_coe, id_eq]
simp