Module: Mathlib.AlgebraicGeometry.Group.Affine

Goal state before:
pp: case h₀
R✝¹ R✝ A : CommRingCat
X M G : Scheme
R S T : Type u
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Bialgebra R T
⊢ (Over.Hom.left
          (μ ≫
            Hom.asOver
              (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
              (Spec (of S))) ≫
        (pullbackSpecIso' R S T).inv) ≫
      pullback.fst (Spec (of S) ↘ Spec (of R)) (Spec (of T) ↘ Spec (of R)) =
    (Over.Hom.left
          ((Hom.asOver
                (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
                (Spec (of S)) ⊗ₘ
              Hom.asOver
                (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
                (Spec (of S))) ≫
            μ) ≫
        (pullbackSpecIso' R S T).inv) ≫
      pullback.fst (Spec (of S) ↘ Spec (of R)) (Spec (of T) ↘ Spec (of R))

pp: case h₁
R✝¹ R✝ A : CommRingCat
X M G : Scheme
R S T : Type u
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Bialgebra R T
⊢ (Over.Hom.left
          (μ ≫
            Hom.asOver
              (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
              (Spec (of S))) ≫
        (pullbackSpecIso' R S T).inv) ≫
      pullback.snd (Spec (of S) ↘ Spec (of R)) (Spec (of T) ↘ Spec (of R)) =
    (Over.Hom.left
          ((Hom.asOver
                (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
                (Spec (of S)) ⊗ₘ
              Hom.asOver
                (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
                (Spec (of S))) ≫
            μ) ≫
        (pullbackSpecIso' R S T).inv) ≫
      pullback.snd (Spec (of S) ↘ Spec (of R)) (Spec (of T) ↘ Spec (of R))

Tactic:
· have : includeLeftRingHom = algebraMap S (S ⊗[R] T) := rfl
      simp [Scheme.monObjAsOverPullback_mul, pullbackSpecIso', specOverSpec_over, ← Spec.map_comp,
        ← CommRingCat.ofHom_comp, OverClass.asOver, mul_spec_asOver_spec_left, this, Hom.asOver,
        OverClass.asOverHom, pullback.condition]
      rfl

Goal state after:
case h₁
R✝¹ R✝ A : CommRingCat
X M G : Scheme
R S T : Type u
inst✝⁴ : CommRing R
inst✝³ : CommRing S
inst✝² : CommRing T
inst✝¹ : Algebra R S
inst✝ : Bialgebra R T
⊢ (Over.Hom.left
          (μ ≫
            Hom.asOver
              (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
              (Spec (of S))) ≫
        (pullbackSpecIso' R S T).inv) ≫
      pullback.snd (Spec (of S) ↘ Spec (of R)) (Spec (of T) ↘ Spec (of R)) =
    (Over.Hom.left
          ((Hom.asOver
                (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
                (Spec (of S)) ⊗ₘ
              Hom.asOver
                (pullbackSymmetry (Spec (of T) ↘ Spec (of R)) (Spec (of S) ↘ Spec (of R)) ≪≫ pullbackSpecIso' R S T).hom
                (Spec (of S))) ≫
            μ) ≫
        (pullbackSpecIso' R S T).inv) ≫
      pullback.snd (Spec (of S) ↘ Spec (of R)) (Spec (of T) ↘ Spec (of R))