Zulip Chat Archive

Stream: Is there code for X?

Topic: AlgEquiv_invFun_apply


Bolton Bailey (Oct 20 2023 at 13:44):

Do we have this lemma?

lemma AlgEquiv_invFun_apply {R α β : Type} [CommSemiring R] [Semiring α] [Semiring β] [Algebra R α] [Algebra R β]
    (e : α ≃ₐ[R] β) (x : α) : x = (e).toEquiv.invFun ((e) x) := by
  rw [AlgEquiv.toEquiv_eq_coe, Equiv.invFun_as_coe, @Equiv.eq_symm_apply]
  exact rfl

Bolton Bailey (Oct 20 2023 at 13:51):

(and more importantly, can rw_search prove it?)

Eric Rodriguez (Oct 20 2023 at 14:04):

this should be defeq to e.symm $ e x = x no?

Eric Wieser (Oct 20 2023 at 15:35):

invFun should never appear in any lemma statement other than the one that eliminates it


Last updated: Dec 20 2023 at 11:08 UTC