intro σ₁ σ₂ h
Γ : Type
inst✝ : Alphabet Γ
⊢ ∀ (a₁ a₂ : (stringAlgebra Γ).carrier), treeₑ a₁ = treeₑ a₂ → a₁ = a₂
Γ : Type
inst✝ : Alphabet Γ
σ₁ σ₂ : (stringAlgebra Γ).carrier
h : treeₑ σ₁ = treeₑ σ₂
⊢ σ₁ = σ₂