Disjoint extensions with coprime different ideals #
Let A ⊆ B be a finite extension of Dedekind domains and assume that A ⊆ R₁, R₂ ⊆ B are two
subrings such that Frac R₁ ⊔ Frac R₂ = Frac B, Frac R₁ and Frac R₂ are linearly disjoint
over Frac A, and that 𝓓(R₁/A) and 𝓓(R₂/A) are coprime where 𝓓 denotes the different ideal
and Frac R denotes the fraction field of a domain R.
Main results and definitions #
FractionalIdeal.differentIdeal_eq_map_differentIdeal:𝓓(B/R₁) = 𝓓(R₂/A)FractionalIdeal.differentIdeal_eq_differentIdeal_mul_differentIdeal_of_isCoprime:𝓓(B/A) = 𝓓(R₁/A) * 𝓓(R₂/A).Module.Basis.ofIsCoprimeDifferentIdeal: Construct aR₁-basis ofBby lifting anA-basis ofR₂.IsDedekindDomain.range_sup_range_eq_top_of_isCoprime_differentIdeal:Bis generated (as anA-algebra) byR₁andR₂.
Let A ⊆ B be a finite extension of Dedekind domains and assume that A ⊆ R₁, R₂ ⊆ B are two
subrings such that Frac R₁ ⊔ Frac R₂ = Frac B, Frac R₁ and Frac R₂ are linearly disjoint
over Frac A, and that 𝓓(R₁/A) and 𝓓(R₂/A) are coprime where 𝓓 denotes the different ideal
and Frac R denotes the fraction field of a domain R.
We have 𝓓(B/A) = 𝓓(R₁/A) * 𝓓(R₂/A).
Let A ⊆ B be a finite extension of Dedekind domains and assume that A ⊆ R₁, R₂ ⊆ B are two
subrings such that Frac R₁ ⊔ Frac R₂ = Frac B, Frac R₁ and Frac R₂ are linearly disjoint
over Frac A, and that 𝓓(R₁/A) and 𝓓(R₂/A) are coprime where 𝓓 denotes the different ideal
and Frac R denotes the fraction field of a domain R.
Construct a R₁-basis of B by lifting an A-basis of R₂.
Equations
- Module.Basis.ofIsCoprimeDifferentIdeal A B R₁ R₂ h₁ h₂ h₃ b = Module.Basis.mk ⋯ ⋯
Instances For
Let A ⊆ B be a finite extension of Dedekind domains and assume that A ⊆ R₁, R₂ ⊆ B are two
subrings such that Frac R₁ ⊔ Frac R₂ = Frac B, Frac R₁ and Frac R₂ are linearly disjoint
over Frac A, and that 𝓓(R₁/A) and 𝓓(R₂/A) are coprime where 𝓓 denotes the different ideal
and Frac R denotes the fraction field of a domain R.
Then B is generated (as an A-algebra) by R₁ and R₂.