Theorem: ClassGroup.mk0_integralRep
File: Mathlib/RingTheory/ClassGroup.lean

Proof steps:
state_before: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
⊢ mk0 ⟨integralRep ↑I, ⋯⟩ = mk I
state_after: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
⊢ ∃ x, I * (toPrincipalIdeal R (FractionRing R)) x = (FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩
tactic: rw [← ClassGroup.mk_mk0 (FractionRing R), eq_comm, ClassGroup.mk_eq_mk]
state_before: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
⊢ ∃ x, I * (toPrincipalIdeal R (FractionRing R)) x = (FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩
state_after: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ ∃ x, I * (toPrincipalIdeal R (FractionRing R)) x = (FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩
tactic: have fd_ne_zero : (algebraMap R (FractionRing R)) I.1.den ≠ 0 := by
    exact IsFractionRing.to_map_ne_zero_of_mem_nonZeroDivisors (SetLike.coe_mem _)
state_before: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ ∃ x, I * (toPrincipalIdeal R (FractionRing R)) x = (FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩
state_after: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ I * (toPrincipalIdeal R (FractionRing R)) (Units.mk0 ((algebraMap R (FractionRing R)) ↑(↑I).den) fd_ne_zero) =
    (FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩
tactic: refine ⟨Units.mk0 (algebraMap R _ I.1.den) fd_ne_zero, ?_⟩
state_before: R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ I * (toPrincipalIdeal R (FractionRing R)) (Units.mk0 ((algebraMap R (FractionRing R)) ↑(↑I).den) fd_ne_zero) =
    (FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩
state_after: case a
R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ ↑(I * (toPrincipalIdeal R (FractionRing R)) (Units.mk0 ((algebraMap R (FractionRing R)) ↑(↑I).den) fd_ne_zero)) =
    ↑((FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩)
tactic: apply Units.ext
state_before: case a
R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ ↑(I * (toPrincipalIdeal R (FractionRing R)) (Units.mk0 ((algebraMap R (FractionRing R)) ↑(↑I).den) fd_ne_zero)) =
    ↑((FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩)
state_after: case a
R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ spanSingleton R⁰ ((algebraMap R (FractionRing R)) ↑(↑I).den) * ↑I =
    ↑((FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩)
tactic: rw [mul_comm, val_mul, coe_toPrincipalIdeal, val_mk0]
state_before: case a
R : Type u_1
K : Type u_2
L : Type u_3
inst✝¹¹ : CommRing R
inst✝¹⁰ : Field K
inst✝⁹ : Field L
inst✝⁸ : DecidableEq L
inst✝⁷ : Algebra R K
inst✝⁶ : IsFractionRing R K
inst✝⁵ : Algebra K L
inst✝⁴ : FiniteDimensional K L
inst✝³ : Algebra R L
inst✝² : IsScalarTower R K L
inst✝¹ : IsDomain R
inst✝ : IsDedekindDomain R
I : (FractionalIdeal R⁰ (FractionRing R))ˣ
fd_ne_zero : (algebraMap R (FractionRing R)) ↑(↑I).den ≠ 0
⊢ spanSingleton R⁰ ((algebraMap R (FractionRing R)) ↑(↑I).den) * ↑I =
    ↑((FractionalIdeal.mk0 (FractionRing R)) ⟨integralRep ↑I, ⋯⟩)
state_after: no goals
tactic: exact FractionalIdeal.den_mul_self_eq_num' R⁰ (FractionRing R) I