Localization over left Ore sets. #
This file defines the localization of a monoid over a left Ore set and proves its universal mapping property.
Notation #
Introduces the notation R[S⁻¹] for the Ore localization of a monoid R at a right Ore
subset S. Also defines a new heterogeneous division notation r /ₒ s for a numerator r : R and
a denominator s : S.
References #
- https://ncatlab.org/nlab/show/Ore+localization
- [Zoran Škoda, Noncommutative localization in noncommutative geometry][skoda2006]
Tags #
localization, Ore, non-commutative
Implementation detail #
Some of the declarations are marked reducible to avoid diamonds with
Mathlib/Algebra/Module/LocalizedModule/Basic.lean. This causes a significant performance
regression, most notably in Mathlib/AlgebraicGeometry/AffineSpace.lean.
Also see https://github.com/leanprover-community/mathlib4/pull/31862.
We shall investigate if there are ways to improve performances. For example by introducing
typeclasses to unify the two constructions on this and LocalizedModule, or by marking some
downstream constructions (e.g. Spec.structureSheaf) as irreducible.
The setoid on R × S used for the Ore localization.
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The Ore localization of a monoid and a submonoid fulfilling the Ore condition.
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The Ore localization of an additive monoid and a submonoid fulfilling the Ore condition.
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The Ore localization of a monoid and a submonoid fulfilling the Ore condition.
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The division in the Ore localization X[S⁻¹], as a fraction of an element of X and S.
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The subtraction in the Ore localization,
as a difference of an element of X and S.
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The division in the Ore localization X[S⁻¹], as a fraction of an element of X and S.
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The subtraction in the Ore localization,
as a difference of an element of X and S.
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A difference r -ₒ s is equal to its expansion by an
arbitrary translation t if t + s ∈ S.
A difference is equal to its expansion by a summand from S.
Fractions which differ by a factor of the numerator can be proven equal if
those factors expand to equal elements of R.
Differences whose minuends differ by a common summand can be proven equal if
those summands expand to equal elements of R.
A function or predicate over X and S can be lifted to X[S⁻¹] if it is invariant
under expansion on the left.
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A function or predicate over X and S can be lifted to the localization if it
is invariant under expansion on the left.
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A version of liftExpand used to simultaneously lift functions with two arguments
in X[S⁻¹].
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A version of liftExpand used to simultaneously lift functions with two arguments.
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The scalar multiplication on the Ore localization of monoids.
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the vector addition on the Ore localization of additive monoids.
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A characterization lemma for the scalar multiplication on the Ore localization, allowing for a choice of Ore numerator and Ore denominator.
A characterization lemma for the vector addition on the Ore localization, allowing for a choice of Ore minuend and Ore subtrahend.
A characterization lemma for the multiplication on the Ore localization, allowing for a choice of Ore numerator and Ore denominator.
A characterization lemma for the addition on the Ore localization, allowing for a choice of Ore minuend and Ore subtrahend.
Another characterization lemma for the scalar multiplication on the Ore localization delivering Ore witnesses and conditions bundled in a sigma type.
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Another characterization lemma for the vector addition on the Ore localization delivering Ore witnesses and conditions bundled in a sigma type.
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Another characterization lemma for the multiplication on the Ore localization delivering Ore witnesses and conditions bundled in a sigma type.
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Another characterization lemma for the addition on the Ore localization delivering Ore witnesses and conditions bundled in a sigma type.
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1 in the localization, defined as 1 /ₒ 1.
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0 in the additive localization, defined as 0 -ₒ 0.
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The fraction s /ₒ 1 as a unit in R[S⁻¹], where s : S.
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The difference s -ₒ 0 as an additive unit.
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The multiplicative homomorphism from R to R[S⁻¹], mapping r : R to the
fraction r /ₒ 1.
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The additive homomorphism from R to AddOreLocalization R S,
mapping r : R to the difference r -ₒ 0.
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The universal lift from a morphism R →* T, which maps elements of S to units of T,
to a morphism R[S⁻¹] →* T.
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The universal lift from a morphism R →+ T, which maps elements of S to
additive-units of T, to a morphism AddOreLocalization R S →+ T.
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The universal morphism universalMulHom is unique.
The universal morphism universalAddHom is unique.
Scalar multiplication in a monoid localization.
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Vector addition in an additive monoid localization.
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0 in the localization, defined as 0 /ₒ 1.