English
A Mem-submodule condition is equivalent when holding for all i in support and all i generally.
Русский
Условие подмодуля памяти эквивалентно для всех i и по всей поддержке.
LaTeX
$$theorem forall_mem_support_invtSubmodule_iff$$
Lean4
theorem forall_mem_support_invtSubmodule_iff (q : Submodule R M) :
(∀ i ∈ b.support, q ∈ invtSubmodule (P.reflection i)) ↔ (∀ i, q ∈ invtSubmodule (P.reflection i)) :=
by
refine ⟨fun hq i ↦ ?_, fun hq i _ ↦ hq i⟩
letI := P.indexNeg
have (j : ι) : P.reflection (-j) = P.reflection j := by ext x; simp [reflection_apply, two_smul]
refine b.induction_reflect i (by simp_all) hq ?_
clear i
intro i j hi hj
rw [reflection_reflectionPerm]
exact Module.End.invtSubmodule.comp _ (Module.End.invtSubmodule.comp _ (hq j hj) hi) (hq j hj)