Module: Mathlib.RingTheory.Smooth.Fiber

Goal state before:
pp: R : Type u_1
S : Type u_2
P : Type u_3
inst✝¹⁴ : CommRing R
inst✝¹³ : CommRing S
inst✝¹² : Algebra R S
inst✝¹¹ : Module.Flat R S
inst✝¹⁰ : CommRing P
inst✝⁹ : Algebra R P
inst✝⁸ : Algebra P S
inst✝⁷ : IsScalarTower R P S
inst✝⁶ : IsLocalRing R
inst✝⁵ : IsLocalRing S
inst✝⁴ : IsLocalHom (algebraMap R S)
inst✝³ : FormallySmooth 𝓀[R] (𝓀[R] ⊗[R] S)
inst✝² : FormallySmooth R P
inst✝¹ : Module.Free P Ω[P⁄R]
inst✝ : Module.Finite P Ω[P⁄R]
h₁ : Function.Surjective ⇑(algebraMap P S)
h₂ : (RingHom.ker (algebraMap P S)).FG
Sp : Type (max u_1 u_2) := 𝓀[R] ⊗[R] S
Pp : Type (max u_1 u_3) := 𝓀[R] ⊗[R] P
φ : Pp →ₐ[𝓀[R]] Sp := TensorProduct.map (AlgHom.id 𝓀[R] 𝓀[R]) (IsScalarTower.toAlgHom R P S)
ψ : Sp →ₐ[R] 𝓀[S] := TensorProduct.lift (IsScalarTower.toAlgHom R 𝓀[R] 𝓀[S]) (IsScalarTower.toAlgHom R S 𝓀[S]) ⋯
algInst✝³ : Algebra Pp Sp := φ.toAlgebra
algInst✝² : Algebra P Sp := (φ.comp (algebraMap P Pp)).toAlgebra
algInst✝¹ : Algebra Sp 𝓀[S] := ψ.toAlgebra
algInst✝ : Algebra Pp 𝓀[S] := (ψ.comp φ.toRingHom).toAlgebra
scalarTowerInst✝¹ : IsScalarTower P Pp Sp := IsScalarTower.of_algebraMap_eq' (Eq.refl (algebraMap P Sp))
scalarTowerInst✝ : IsScalarTower Pp Sp 𝓀[S] := IsScalarTower.of_algebraMap_eq' (Eq.refl (algebraMap Pp 𝓀[S]))
this✝⁴ : IsScalarTower 𝓀[R] Pp Sp
this✝³ : IsScalarTower R Sp 𝓀[S]
this✝² : IsScalarTower P S Sp
this✝¹ : IsScalarTower S Sp 𝓀[S]
this✝ : IsScalarTower P Sp 𝓀[S]
this : IsScalarTower P Pp 𝓀[S]
⊢ FormallySmooth R S

Tactic:
let ePp : Pp ≃ₐ[P] P ⊗[R] 𝓀[R] := { __ := TensorProduct.comm _ _ _, commutes' _ := rfl }

Goal state after:
R : Type u_1
S : Type u_2
P : Type u_3
inst✝¹⁴ : CommRing R
inst✝¹³ : CommRing S
inst✝¹² : Algebra R S
inst✝¹¹ : Module.Flat R S
inst✝¹⁰ : CommRing P
inst✝⁹ : Algebra R P
inst✝⁸ : Algebra P S
inst✝⁷ : IsScalarTower R P S
inst✝⁶ : IsLocalRing R
inst✝⁵ : IsLocalRing S
inst✝⁴ : IsLocalHom (algebraMap R S)
inst✝³ : FormallySmooth 𝓀[R] (𝓀[R] ⊗[R] S)
inst✝² : FormallySmooth R P
inst✝¹ : Module.Free P Ω[P⁄R]
inst✝ : Module.Finite P Ω[P⁄R]
h₁ : Function.Surjective ⇑(algebraMap P S)
h₂ : (RingHom.ker (algebraMap P S)).FG
Sp : Type (max u_1 u_2) := 𝓀[R] ⊗[R] S
Pp : Type (max u_1 u_3) := 𝓀[R] ⊗[R] P
φ : Pp →ₐ[𝓀[R]] Sp := TensorProduct.map (AlgHom.id 𝓀[R] 𝓀[R]) (IsScalarTower.toAlgHom R P S)
ψ : Sp →ₐ[R] 𝓀[S] := TensorProduct.lift (IsScalarTower.toAlgHom R 𝓀[R] 𝓀[S]) (IsScalarTower.toAlgHom R S 𝓀[S]) ⋯
algInst✝³ : Algebra Pp Sp := φ.toAlgebra
algInst✝² : Algebra P Sp := (φ.comp (algebraMap P Pp)).toAlgebra
algInst✝¹ : Algebra Sp 𝓀[S] := ψ.toAlgebra
algInst✝ : Algebra Pp 𝓀[S] := (ψ.comp φ.toRingHom).toAlgebra
scalarTowerInst✝¹ : IsScalarTower P Pp Sp := IsScalarTower.of_algebraMap_eq' (Eq.refl (algebraMap P Sp))
scalarTowerInst✝ : IsScalarTower Pp Sp 𝓀[S] := IsScalarTower.of_algebraMap_eq' (Eq.refl (algebraMap Pp 𝓀[S]))
this✝⁴ : IsScalarTower 𝓀[R] Pp Sp
this✝³ : IsScalarTower R Sp 𝓀[S]
this✝² : IsScalarTower P S Sp
this✝¹ : IsScalarTower S Sp 𝓀[S]
this✝ : IsScalarTower P Sp 𝓀[S]
this : IsScalarTower P Pp 𝓀[S]
ePp : Pp ≃ₐ[P] P ⊗[R] 𝓀[R] :=
  let __spread.0 := TensorProduct.comm R 𝓀[R] P;
  { toEquiv := __spread.0.toEquiv, map_mul' := ⋯, map_add' := ⋯, commutes' := ⋯ }
⊢ FormallySmooth R S