case step.refl.inst.step.inst e _ f' f => exact e.nonrepeatable f |>.elim
α : Type
inst✝ : Proper α
s s₁ s₂ s₂✝¹ s₃✝ : State α
a_ih✝ : Steps s₂✝¹ s₂ → State.Nontrivial s₂✝¹ → s₃✝.tag = s₂.tag → s₃✝.progress = s₂.progress → s₃✝ = s₂
ht : s₃✝.tag = s₂.tag
hp : s₃✝.progress = s₂.progress
n : State.Nontrivial s₂
e : s₂ ↓ᵢ| s₂✝¹
s₂✝ : State α
f' : Steps s₂✝ s₃✝
f : s₂✝¹ ↓ᵢ| s₂✝
⊢ s₃✝ = s₂
no goals