Germ of a function at a filter #
The germ of a function f : α → β
at a filter l : Filter α
is the equivalence class of f
with respect to the equivalence relation EventuallyEq l
: f ≈ g
means ∀ᶠ x in l, f x = g x
.
Main definitions #
We define
Filter.Germ l β
to be the space of germs of functionsα → β
at a filterl : Filter α
;- coercion from
α → β
toGerm l β
:(f : Germ l β)
is the germ off : α → β
atl : Filter α
; this coercion is declared asCoeTC
; (const l c : Germ l β)
is the germ of the constant functionfun x : α ↦ c
at a filterl
;- coercion from
β
toGerm l β
:(↑c : Germ l β)
is the germ of the constant functionfun x : α ↦ c
at a filterl
; this coercion is declared asCoeTC
; map (F : β → γ) (f : Germ l β)
to be the composition of a functionF
and a germf
;map₂ (F : β → γ → δ) (f : Germ l β) (g : Germ l γ)
to be the germ offun x ↦ F (f x) (g x)
atl
;f.Tendsto lb
: we say that a germf : Germ l β
tends to a filterlb
if its representatives tend tolb
alongl
;f.compTendsto g hg
andf.compTendsto' g hg
: givenf : Germ l β
and a functiong : γ → α
(resp., a germg : Germ lc α
), ifg
tends tol
alonglc
, then the compositionf ∘ g
is a well-defined germ atlc
;Germ.liftPred
,Germ.liftRel
: lift a predicate or a relation to the space of germs:(f : Germ l β).liftPred p
means∀ᶠ x in l, p (f x)
, and similarly for a relation.
We also define map (F : β → γ) : Germ l β → Germ l γ
sending each germ f
to F ∘ f
.
For each of the following structures we prove that if β
has this structure, then so does
Germ l β
:
- one-operation algebraic structures up to
CommGroup
; MulZeroClass
,Distrib
,Semiring
,CommSemiring
,Ring
,CommRing
;MulAction
,DistribMulAction
,Module
;Preorder
,PartialOrder
, andLattice
structures, as well asBoundedOrder
;OrderedCancelCommMonoid
andOrderedCancelAddCommMonoid
.
Tags #
filter, germ
Setoid used to define the space of germs.
Equations
- Filter.germSetoid l β = { r := Filter.EventuallyEq l, iseqv := (_ : Equivalence (Filter.EventuallyEq l)) }
Instances For
The space of germs of functions α → β
at a filter l
.
Equations
- Filter.Germ l β = Quotient (Filter.germSetoid l β)
Instances For
Setoid used to define the filter product. This is a dependent version of
Filter.germSetoid
.
Equations
- Filter.productSetoid l ε = { r := fun (f g : (a : α) → ε a) => ∀ᶠ (a : α) in l, f a = g a, iseqv := (_ : Equivalence fun (f g : (a : α) → ε a) => ∀ᶠ (a : α) in l, f a = g a) }
Instances For
The filter product (a : α) → ε a
at a filter l
. This is a dependent version of
Filter.Germ
.
Equations
- Filter.Product l ε = Quotient (Filter.productSetoid l ε)
Instances For
Equations
- Filter.Product.coeTC = { coe := Quotient.mk' }
Equations
- Filter.Product.inhabited = { default := Quotient.mk' fun (a : α) => default }
Equations
- Filter.Germ.ofFun = Quotient.mk'
Instances For
Equations
- Filter.Germ.instCoeTCForAllGerm = { coe := Filter.Germ.ofFun }
Equations
- ↑b = ↑fun (x : α) => b
Instances For
Equations
- Filter.Germ.coeTC = { coe := Filter.Germ.const }
Given a map F : (α → β) → (γ → δ)
that sends functions eventually equal at l
to functions
eventually equal at lc
, returns a map from Germ l β
to Germ lc δ
.
Equations
- Filter.Germ.map' F hF = Quotient.map' F hF
Instances For
Given a germ f : Germ l β
and a function F : (α → β) → γ
sending eventually equal functions
to the same value, returns the value F
takes on functions having germ f
at l
.
Equations
- Filter.Germ.liftOn f F hF = Quotient.liftOn' f F hF
Instances For
Alias of the reverse direction of Filter.Germ.coe_eq
.
Lift a function β → γ
to a function Germ l β → Germ l γ
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Lift a binary function β → γ → δ
to a function Germ l β → Germ l γ → Germ l δ
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
A germ at l
of maps from α
to β
tends to lb : Filter β
if it is represented by a map
which tends to lb
along l
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Alias of the reverse direction of Filter.Germ.coe_tendsto
.
Given two germs f : Germ l β
, and g : Germ lc α
, where l : Filter α
, if g
tends to l
,
then the composition f ∘ g
is well-defined as a germ at lc
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Given a germ f : Germ l β
and a function g : γ → α
, where l : Filter α
, if g
tends
to l
along lc : Filter γ
, then the composition f ∘ g
is well-defined as a germ at lc
.
Equations
- Filter.Germ.compTendsto f g hg = Filter.Germ.compTendsto' f ↑g (_ : Filter.Germ.Tendsto (↑g) l)
Instances For
Lift a predicate on β
to Germ l β
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Lift a relation r : β → γ → Prop
to Germ l β → Germ l γ → Prop
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Equations
- Filter.Germ.inhabited = { default := ↑default }
Equations
- Filter.Germ.add = { add := Filter.Germ.map₂ fun (x x_1 : M) => x + x_1 }
Equations
- Filter.Germ.mul = { mul := Filter.Germ.map₂ fun (x x_1 : M) => x * x_1 }
Equations
- Filter.Germ.zero = { zero := ↑0 }
Equations
- Filter.Germ.one = { one := ↑1 }
Equations
- Filter.Germ.addSemigroup = AddSemigroup.mk (_ : ∀ (a b c : Filter.Germ l M), a + b + c = a + (b + c))
Equations
- Filter.Germ.semigroup = Semigroup.mk (_ : ∀ (a b c : Filter.Germ l M), a * b * c = a * (b * c))
Equations
- Filter.Germ.addCommSemigroup = AddCommSemigroup.mk (_ : ∀ (q₁ q₂ : Quotient (Filter.germSetoid l M)), q₁ + q₂ = q₂ + q₁)
Equations
- Filter.Germ.commSemigroup = CommSemigroup.mk (_ : ∀ (q₁ q₂ : Quotient (Filter.germSetoid l M)), q₁ * q₂ = q₂ * q₁)
Equations
- (_ : IsLeftCancelAdd (Filter.Germ l M)) = (_ : IsLeftCancelAdd (Filter.Germ l M))
Equations
- (_ : IsLeftCancelMul (Filter.Germ l M)) = (_ : IsLeftCancelMul (Filter.Germ l M))
Equations
- (_ : IsRightCancelAdd (Filter.Germ l M)) = (_ : IsRightCancelAdd (Filter.Germ l M))
Equations
- (_ : IsRightCancelMul (Filter.Germ l M)) = (_ : IsRightCancelMul (Filter.Germ l M))
Equations
- (_ : IsCancelAdd (Filter.Germ l M)) = (_ : IsCancelAdd (Filter.Germ l M))
Equations
- (_ : IsCancelMul (Filter.Germ l M)) = (_ : IsCancelMul (Filter.Germ l M))
Equations
- Filter.Germ.addLeftCancelSemigroup = let src := Filter.Germ.addSemigroup; AddLeftCancelSemigroup.mk (_ : ∀ (x x_1 x_2 : Filter.Germ l M), x + x_1 = x + x_2 → x_1 = x_2)
Equations
- Filter.Germ.leftCancelSemigroup = let src := Filter.Germ.semigroup; LeftCancelSemigroup.mk (_ : ∀ (x x_1 x_2 : Filter.Germ l M), x * x_1 = x * x_2 → x_1 = x_2)
Equations
- Filter.Germ.addRightCancelSemigroup = let src := Filter.Germ.addSemigroup; AddRightCancelSemigroup.mk (_ : ∀ (x x_1 x_2 : Filter.Germ l M), x + x_1 = x_2 + x_1 → x = x_2)
Equations
- Filter.Germ.rightCancelSemigroup = let src := Filter.Germ.semigroup; RightCancelSemigroup.mk (_ : ∀ (x x_1 x_2 : Filter.Germ l M), x * x_1 = x_2 * x_1 → x = x_2)
Equations
- Filter.Germ.addZeroClass = AddZeroClass.mk (_ : ∀ (q : Quotient (Filter.germSetoid l M)), 0 + q = q) (_ : ∀ (q : Quotient (Filter.germSetoid l M)), q + 0 = q)
Equations
- Filter.Germ.mulOneClass = MulOneClass.mk (_ : ∀ (q : Quotient (Filter.germSetoid l M)), 1 * q = q) (_ : ∀ (q : Quotient (Filter.germSetoid l M)), q * 1 = q)
Equations
- Filter.Germ.vadd = { vadd := fun (n : M) => Filter.Germ.map fun (x : G) => n +ᵥ x }
Equations
- Filter.Germ.smul = { smul := fun (n : M) => Filter.Germ.map fun (x : G) => n • x }
Equations
- Filter.Germ.pow = { pow := fun (f : Filter.Germ l G) (n : M) => Filter.Germ.map (fun (x : G) => x ^ n) f }
Equations
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Equations
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Coercion from functions to germs as an additive monoid homomorphism.
Equations
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Instances For
Coercion from functions to germs as a monoid homomorphism.
Equations
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Instances For
Equations
- Filter.Germ.addCommMonoid = AddCommMonoid.mk (_ : ∀ (a b : Filter.Germ l M), a + b = b + a)
Equations
- Filter.Germ.commMonoid = CommMonoid.mk (_ : ∀ (a b : Filter.Germ l M), a * b = b * a)
Equations
- Filter.Germ.addMonoidWithOne = let src := Filter.Germ.natCast; let src_1 := Filter.Germ.addMonoid; let src_2 := Filter.Germ.one; AddMonoidWithOne.mk
Equations
- Filter.Germ.addCommMonoidWithOne = AddCommMonoidWithOne.mk (_ : ∀ (a b : Filter.Germ l M), a + b = b + a)
Equations
- Filter.Germ.neg = { neg := Filter.Germ.map Neg.neg }
Equations
- Filter.Germ.inv = { inv := Filter.Germ.map Inv.inv }
Equations
- Filter.Germ.sub = { sub := Filter.Germ.map₂ fun (x x_1 : M) => x - x_1 }
Equations
- Filter.Germ.div = { div := Filter.Germ.map₂ fun (x x_1 : M) => x / x_1 }
Equations
- Filter.Germ.involutiveNeg = InvolutiveNeg.mk (_ : ∀ (q : Quotient (Filter.germSetoid l G)), - -q = q)
Equations
- Filter.Germ.involutiveInv = InvolutiveInv.mk (_ : ∀ (q : Quotient (Filter.germSetoid l G)), q⁻¹⁻¹ = q)
Equations
- Filter.Germ.negZeroClass = NegZeroClass.mk (_ : ↑((fun (x : α → G) => Neg.neg ∘ x) fun (x : α) => 0) = ↑fun (x : α) => 0)
Equations
- Filter.Germ.invOneClass = InvOneClass.mk (_ : ↑((fun (x : α → G) => Inv.inv ∘ x) fun (x : α) => 1) = ↑fun (x : α) => 1)
Equations
- Filter.Germ.subNegMonoid = let src := Filter.Germ.addMonoid; let src_1 := Filter.Germ.neg; let src_2 := Filter.Germ.sub; SubNegMonoid.mk fun (z : ℤ) (f : Filter.Germ l G) => z • f
Equations
- Filter.Germ.divInvMonoid = let src := Filter.Germ.monoid; let src_1 := Filter.Germ.inv; let src_2 := Filter.Germ.div; DivInvMonoid.mk fun (z : ℤ) (f : Filter.Germ l G) => f ^ z
Equations
- One or more equations did not get rendered due to their size.
Equations
- One or more equations did not get rendered due to their size.
Equations
- Filter.Germ.addGroup = AddGroup.mk (_ : ∀ (q : Quotient (Filter.germSetoid l G)), -q + q = 0)
Equations
- Filter.Germ.addCommGroup = AddCommGroup.mk (_ : ∀ (a b : Filter.Germ l G), a + b = b + a)
Equations
- Filter.Germ.commGroup = CommGroup.mk (_ : ∀ (a b : Filter.Germ l G), a * b = b * a)
Equations
- One or more equations did not get rendered due to their size.
Equations
- (_ : Nontrivial (Filter.Germ l R)) = (_ : Nontrivial (Filter.Germ l R))
Equations
- Filter.Germ.mulZeroClass = MulZeroClass.mk (_ : ∀ (q : Quotient (Filter.germSetoid l R)), 0 * q = 0) (_ : ∀ (q : Quotient (Filter.germSetoid l R)), q * 0 = 0)
Equations
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Equations
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Equations
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Equations
- Filter.Germ.nonUnitalSemiring = NonUnitalSemiring.mk (_ : ∀ (a b c : Filter.Germ l R), a * b * c = a * (b * c))
Equations
- One or more equations did not get rendered due to their size.
Equations
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Equations
- Filter.Germ.nonUnitalRing = NonUnitalRing.mk (_ : ∀ (a b c : Filter.Germ l R), a * b * c = a * (b * c))
Equations
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Equations
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Equations
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Equations
- Filter.Germ.nonUnitalCommSemiring = NonUnitalCommSemiring.mk (_ : ∀ (a b : Filter.Germ l R), a * b = b * a)
Equations
- Filter.Germ.commSemiring = CommSemiring.mk (_ : ∀ (a b : Filter.Germ l R), a * b = b * a)
Equations
- Filter.Germ.nonUnitalCommRing = let src := Filter.Germ.nonUnitalRing; let src_1 := Filter.Germ.commSemigroup; NonUnitalCommRing.mk (_ : ∀ (a b : Filter.Germ l R), a * b = b * a)
Equations
- Filter.Germ.commRing = CommRing.mk (_ : ∀ (a b : Filter.Germ l R), a * b = b * a)
Coercion (α → R) → Germ l R
as a RingHom
.
Equations
- One or more equations did not get rendered due to their size.
Instances For
Equations
- Filter.Germ.instVAdd' = { vadd := Filter.Germ.map₂ fun (x : M) (x_1 : β) => x +ᵥ x_1 }
Equations
- Filter.Germ.instSMul' = { smul := Filter.Germ.map₂ fun (x : M) (x_1 : β) => x • x_1 }
Equations
- Filter.Germ.addAction = AddAction.mk (_ : ∀ (f : Filter.Germ l β), 0 +ᵥ f = f) (_ : ∀ (c₁ c₂ : M) (f : Filter.Germ l β), c₁ + c₂ +ᵥ f = c₁ +ᵥ (c₂ +ᵥ f))
Equations
- Filter.Germ.mulAction = MulAction.mk (_ : ∀ (f : Filter.Germ l β), 1 • f = f) (_ : ∀ (c₁ c₂ : M) (f : Filter.Germ l β), (c₁ * c₂) • f = c₁ • c₂ • f)
Equations
- Filter.Germ.addAction' = AddAction.mk (_ : ∀ (f : Filter.Germ l β), 0 +ᵥ f = f) (_ : ∀ (c₁ c₂ : Filter.Germ l M) (f : Filter.Germ l β), c₁ + c₂ +ᵥ f = c₁ +ᵥ (c₂ +ᵥ f))
Equations
- Filter.Germ.mulAction' = MulAction.mk (_ : ∀ (f : Filter.Germ l β), 1 • f = f) (_ : ∀ (c₁ c₂ : Filter.Germ l M) (f : Filter.Germ l β), (c₁ * c₂) • f = c₁ • c₂ • f)
Equations
- Filter.Germ.distribMulAction' = DistribMulAction.mk (_ : ∀ (c : Filter.Germ l M), c • 0 = 0) (_ : ∀ (c : Filter.Germ l M) (f g : Filter.Germ l N), c • (f + g) = c • f + c • g)
Equations
- Filter.Germ.module' = Module.mk (_ : ∀ (c₁ c₂ : Filter.Germ l R) (f : Filter.Germ l M), (c₁ + c₂) • f = c₁ • f + c₂ • f) (_ : ∀ (f : Filter.Germ l M), 0 • f = 0)
Equations
- Filter.Germ.le = { le := Filter.Germ.LiftRel fun (x x_1 : β) => x ≤ x_1 }
Equations
- Filter.Germ.preorder = Preorder.mk (_ : ∀ (f : Filter.Germ l β), f ≤ f) (_ : ∀ (f₁ f₂ f₃ : Filter.Germ l β), f₁ ≤ f₂ → f₂ ≤ f₃ → f₁ ≤ f₃)
Equations
- Filter.Germ.partialOrder = let src := Filter.Germ.preorder; PartialOrder.mk (_ : ∀ (f g : Filter.Germ l β), f ≤ g → g ≤ f → f = g)
Equations
- Filter.Germ.orderBot = OrderBot.mk (_ : ∀ (f : Filter.Germ l β), ⊥ ≤ f)
Equations
- Filter.Germ.orderTop = OrderTop.mk (_ : ∀ (f : Filter.Germ l β), f ≤ ⊤)
Equations
- Filter.Germ.instBoundedOrderGermLe = let src := Filter.Germ.orderBot; let src_1 := Filter.Germ.orderTop; BoundedOrder.mk
Equations
- Filter.Germ.sup = { sup := Filter.Germ.map₂ fun (x x_1 : β) => x ⊔ x_1 }
Equations
- Filter.Germ.inf = { inf := Filter.Germ.map₂ fun (x x_1 : β) => x ⊓ x_1 }
Equations
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Equations
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Equations
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Equations
- Filter.Germ.distribLattice = let src := Filter.Germ.semilatticeSup; let src_1 := Filter.Germ.semilatticeInf; DistribLattice.mk (_ : ∀ (f g h : Filter.Germ l β), (f ⊔ g) ⊓ (f ⊔ h) ≤ f ⊔ g ⊓ h)
Equations
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Equations
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Equations
- Filter.Germ.orderedAddCancelCommMonoid = let src := Filter.Germ.orderedAddCommMonoid; OrderedCancelAddCommMonoid.mk (_ : ∀ (f g h : Filter.Germ l β), f + g ≤ f + h → g ≤ h)
Equations
- Filter.Germ.orderedCancelCommMonoid = let src := Filter.Germ.orderedCommMonoid; OrderedCancelCommMonoid.mk (_ : ∀ (f g h : Filter.Germ l β), f * g ≤ f * h → g ≤ h)
Equations
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Equations
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Equations
- (_ : ExistsAddOfLE (Filter.Germ l β)) = (_ : ExistsAddOfLE (Filter.Germ l β))
Equations
- (_ : ExistsMulOfLE (Filter.Germ l β)) = (_ : ExistsMulOfLE (Filter.Germ l β))
Equations
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Equations
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Equations
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Equations
- Filter.Germ.orderedCommSemiring = let src := Filter.Germ.orderedSemiring; let src_1 := Filter.Germ.commSemiring; OrderedCommSemiring.mk (_ : ∀ (a b : Filter.Germ l β), a * b = b * a)
Equations
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Equations
- Filter.Germ.orderedCommRing = let src := Filter.Germ.orderedRing; let src_1 := Filter.Germ.orderedCommSemiring; OrderedCommRing.mk (_ : ∀ (a b : Filter.Germ l β), a * b = b * a)