∀ {α : Type u_2} {β : Type u_3} {γ : Type u_4} [inst : BiheytingAlgebra α] [inst_1 : BiheytingAlgebra β]
  [inst_2 : BiheytingAlgebra γ] {f₁ f₂ : BiheytingHom α β} {g : BiheytingHom β γ},
  Function.Injective ⇑g → (g.comp f₁ = g.comp f₂) = (f₁ = f₂)