case inv _ h =>
  cases' h with w h'
  cases' h' with h1 h2
  exists w
A : Type
R : A → A → Prop
inhabited_A : Nonempty A
confl : confluent R
x y a✝¹ b✝ : A
a✝ : refl_trans_sym_clos R b✝ a✝¹
h : joins R b✝ a✝¹
⊢ joins R a✝¹ b✝
no goals