The push-forward of a list of centres commutes with pull-back along a local analytic isomorphism #
In the proof of [Kol07, Lemma 102] one pulls back by h, restricts to h⁻¹(Eʲ) = Eʲ, and pulls
back by h|_{h⁻¹Eʲ}: the push-forward of a blow-up sequence of a closed submanifold S ⊆ M
(BlowUpSequence.pushforward, [Kol07, Definition 30, 30.3]) pulled back along a local analytic
isomorphism g : N → M is the push-forward, from g⁻¹(S) ⊆ N, of the sequence pulled back along
the restricted local isomorphism g|_{g⁻¹S} : g⁻¹S → S:
IsClosedSubmanifold.restrictInvFunOfPreimage,restrictPartialDiffeomorphOfPreimage,IsClosedSubmanifold.isLocalDiffeomorph_restrictMap,surjective_restrictMap: the restricted map is a local analytic isomorphism between the bundled submanifolds, surjective whengis (the codimension-one lemmas ofHironaka.Resolution.Analytic.OrderReduction.Functoriality, at any codimensions);PushforwardStage.IsPullbackStage P P' G gᵢ, the invariant of the induction: a local isomorphismG : P'.space → P.spaceof ambient stages withP'.sub = G⁻¹(P.sub)and the squareP.incl ∘ gᵢ = G ∘ P'.incl;IsPullbackStage.preimage_imageVal(the pulled-back pushed centre is the pushed pulled-back centre), and the stepisPullbackStage_blowUpStep: the invariant propagates throughblowUpStepalong the liftstepMapofG(liftStepcomposed with the identification of the two blow-ups of the same centre), the next square by uniqueness of lifts on the dense complement of the exceptional divisor, the nextsub-identity bystrictTransformSetbeing the closure of a preimage under the open mapstepMap;BlowUpSequence.pushforward_pullback: the statement above, by induction on the list throughpushforwardAux_pullback(any pair of stages with the invariant;cons_congr_heqandheq_pullback_of_heqidentify the twoconswhose centres are propositionally equal).
This is used to show that the functors built by descent commute with local isomorphisms.
The restricted map at any codimension #
BD.restrictInvFunOfPreimage at any codimension (as in the proof of
[Kol07, Lemma 102]): the local inverse Ψ of h read on the bundled submanifolds.
Equations
Instances For
The value of restrictInvFunOfPreimage on the target of Ψ.
BD.restrictPartialDiffeomorphOfPreimage at any codimension: a local
inverse of h restricted to the bundled submanifolds h⁻¹(S) and S is a partial diffeomorphism
agreeing with the restricted map on h⁻¹(S) ∩ Ψ.source.
Equations
- One or more equations did not get rendered due to their size.
Instances For
BD.isLocalDiffeomorph_restrictMap at any codimension (the proof of [Kol07, Lemma 102]
"h|_{E^j_Y} is also a smooth surjection"): the restriction of a local analytic
isomorphism to the preimage of a closed submanifold is a local analytic isomorphism between the
bundled submanifolds.
BD.surjective_restrictMap at any codimension: the restriction of a surjection to
the preimage of a submanifold is a surjection onto the submanifold.
A chosen blowing-up along a set propositionally equal to Y is a blowing-up with centre
Y.
The lift of h from a blowing-up of a centre propositionally equal to h⁻¹(Y), through the
identification of the two blowings-up, is heterogeneously the lift liftStep.
The invariant #
The invariant of the induction in the proof of [Kol07, Lemma 102], at one stage: G : P'.space → P.space is a local analytic isomorphism of the ambient stages under which the strict transform
P'.sub is the preimage of P.sub and the inclusions of the bundled stages commute with gᵢ : Tᵢ' → Tᵢ.
- isLocalDiffeomorph : IsLocalDiffeomorph (modelWithCornersSelf 𝕜 E) (modelWithCornersSelf 𝕜 E) ⊤ ⇑G
Instances For
The pull-back along G of the pushed-forward centre (j_i)_* Z is the pushed-forward
pulled-back centre (j_i')_* (gᵢ⁻¹ Z).
The step #
The identification of the blowing-up of P'.space along the pushed pulled-back centre with the
blowing-up along the pulled-back pushed centre (the same set, preimage_imageVal).
Equations
- Manifold.PushforwardStage.stepIso h hgᵢ hZ = Manifold.IsBlowUp.diffeomorph ⋯ ⋯ ⋯
Instances For
The lift of G to the next stages: liftStep after the identification stepIso.
Equations
Instances For
The lift lies over G.
The blow-down of a pushed-forward point is the push-forward of its blow-down
(restrictMap_blowUpStep_iso read through the inclusions).
The next square: the two lifts of the inclusions agree, by uniqueness of lifts on the dense complement of the exceptional divisor.
The invariant propagates through one blow-up step.
The induction #
The induction of the proof of [Kol07, Lemma 102] on lists, from any pair of stages with the
invariant:
the pull-back along G of the push-forward of L is the push-forward of the pull-back of L
along gᵢ.
The statement #
The push-forward along a closed submanifold ([Kol07, Definition 30, 30.3]) commutes with
pull-back along a local analytic isomorphism (the proof of [Kol07, Lemma 102]): for a closed
submanifold hS : IsClosedSubmanifold ψ S s, a local analytic isomorphism g : N → M and a list
of centres L on the bundled S, the pull-back along g of the push-forward of L is the
push-forward, from g⁻¹(S), of the pull-back of L along the restricted local isomorphism
g|_{g⁻¹S}.