Localizations away from an element #
Main definitions #
IsLocalization.Away (x : R) Sexpresses thatSis a localization away fromx, as an abbreviation ofIsLocalization (Submonoid.powers x) S.exists_reduced_fraction' (hb : b ≠ 0)produces a reduced fraction of the formb = a * x^nfor somen : ℤand somea : Rthat is not divisible byx.
Implementation notes #
See Mathlib/RingTheory/Localization/Basic.lean for a design overview.
Tags #
localization, ring localization, commutative ring localization, characteristic predicate, commutative ring, field of fractions
Given x : R, the typeclass IsLocalization.Away x S states that S is
isomorphic to the localization of R at the submonoid generated by x.
See IsLocalization.Away.mk for a specialized constructor.
Equations
- IsLocalization.Away x S = IsLocalization (Submonoid.powers x) S
Instances For
Given x : R and a localization map F : R →+* S away from x, invSelf is (F x)⁻¹.
Equations
- IsLocalization.Away.invSelf x = IsLocalization.mk' S 1 ⟨x, ⋯⟩
Instances For
For s : S with S being the localization of R away from x,
this is a choice of (r, n) : R × ℕ such that s * algebraMap R S (x ^ n) = algebraMap R S r.
Equations
- IsLocalization.Away.sec x s = ((IsLocalization.sec (Submonoid.powers x) s).1, Exists.choose ⋯)
Instances For
Specialized constructor for IsLocalization.Away.
If r and r' are associated elements of R, an R-algebra S
is the localization of R away from r if and only of it is the localization of R away from
r'.
Given x : R, a localization map F : R →+* S away from x, and a map of CommSemirings
g : R →+* P such that g x is invertible, the homomorphism induced from S to P sending
z : S to g y * (g x)⁻ⁿ, where y : R, n : ℕ are such that z = F y * (F x)⁻ⁿ.
Equations
Instances For
Given x y : R and localizations S, P away from x and y * x
respectively, the homomorphism induced from S to P.
Equations
Instances For
Given x y : R and localizations S, P away from x and x * y
respectively, the homomorphism induced from S to P.
Equations
Instances For
Given a map f : R →+* S and an element r : R, we may construct a map Rᵣ →+* Sᵣ.
Equations
- IsLocalization.Away.map S Q f r = IsLocalization.map Q f ⋯
Instances For
Given a algebra map f : A →ₐ[R] B and an element a : A, we may construct a map
Aₐ →ₐ[R] Bₐ.
Equations
- IsLocalization.Away.mapₐ Aₚ Bₚ f a = { toRingHom := IsLocalization.Away.map Aₚ Bₚ f.toRingHom a, commutes' := ⋯ }
Instances For
Localizing the localization of R at x at the image of y is the same as localizing
R at y * x. See IsLocalization.Away.mul' for the x * y version.
Localizing the localization of R at x at the image of y is the same as localizing
R at x * y. See IsLocalization.Away.mul for the y * x version.
Localizing the localization of R at x at the image of y is the same as localizing
R at y * x.
Localizing the localization of R at x at the image of y is the same as localizing
R at x * y.
If S₁ is the localization of R away from f and S₂ is the localization away from g,
then any localization T of S₂ away from f is also a localization of S₁ away from g.
The localization away from a unit is isomorphic to the ring.
Equations
- IsLocalization.atUnit R S x e = IsLocalization.atUnits R (Submonoid.powers x) ⋯
Instances For
The localization at one is isomorphic to the ring.
Equations
- IsLocalization.atOne R S = IsLocalization.atUnit R S 1 ⋯
Instances For
Given a map f : R →+* S and an element r : R, such that f r is invertible,
we may construct a map Rᵣ →+* S.
Equations
- Localization.awayLift f r hr = IsLocalization.Away.lift r hr
Instances For
Given a map f : R →+* S and an element r : R, we may construct a map Rᵣ →+* Sᵣ.
Equations
- Localization.awayMap f r = IsLocalization.Away.map (Localization.Away r) (Localization.Away (f r)) f r
Instances For
Given a map f : A →ₐ[R] B and an element a : A, we may construct a map Aₐ →ₐ[R] Bₐ.
Equations
- Localization.awayMapₐ f a = IsLocalization.Away.mapₐ (Localization.Away a) (Localization.Away (f a)) f a
Instances For
The sheaf condition for the structure sheaf on Spec R
for a covering of the whole prime spectrum by basic opens.
selfZPow x (m : ℤ) is x ^ m as an element of the localization away from x.
Equations
- selfZPow x B m = if x_1 : 0 ≤ m then (algebraMap R B) x ^ m.natAbs else IsLocalization.mk' B 1 (Submonoid.pow x m.natAbs)