∀ {X Y : SSet.Truncated 2}
  {x₀ x₁ x₂ : X.obj (Opposite.op { obj := SimplexCategory.mk 0, property := SSet.Truncated.Edge.tensor._proof_1 })}
  {e₀₁ : SSet.Truncated.Edge x₀ x₁} {e₁₂ : SSet.Truncated.Edge x₁ x₂} {e₀₂ : SSet.Truncated.Edge x₀ x₂}
  (hx : e₀₁.CompStruct e₁₂ e₀₂)
  {y₀ y₁ y₂ : Y.obj (Opposite.op { obj := SimplexCategory.mk 0, property := SSet.Truncated.Edge.tensor._proof_1 })}
  {e'₀₁ : SSet.Truncated.Edge y₀ y₁} {e'₁₂ : SSet.Truncated.Edge y₁ y₂} {e'₀₂ : SSet.Truncated.Edge y₀ y₂}
  (hy : e'₀₁.CompStruct e'₁₂ e'₀₂),
  (CategoryTheory.MonoidalCategoryStruct.tensorObj X Y).map
      (SimplexCategory.Truncated.δ₂ 1 SSet.Truncated.Edge._proof_2 SSet.Truncated.Edge.CompStruct._proof_2).op
      (hx.simplex, hy.simplex) =
    (e₀₂.tensor e'₀₂).edge