Transforms along a square of analytic isomorphisms across the models #
The notions attached to an analytic map f : M' → M in the vocabulary of the main theorems —
Hironaka's weak transform [Hir64, p. 142], the reduced transform red(f⁻¹(E) ∪ f⁻¹(D))
[Hir64, Main Theorem II'(N) (iii), p. 156], the isomorphism-over-a-set clause IsAnalyticIsoOver
and properness — transport along a square f ∘ g' = g ∘ f' of analytic isomorphisms g : N ≃ M,
g' : N' ≃ M' across the models (IsModelSquare,
Hironaka/Resolution/Analytic/ModelTransport/IdealSheaf.lean): f' is g⁻¹ ∘ f ∘ g', the same map
read on the re-modelled manifolds. For the main theorems the squares are the identities of
Hironaka/Resolution/Analytic/ModelTransport/Manifold.lean at the stages of a transported
succession (Succession.lean) and at the space of a transported family (Family.lean).
- The weak transform: both sides are the unique ideal sheaf with the colon stalks
(f⁻¹(J)_{a'} : f⁻¹(D)_{a'}^{ν})(IsDivExceptional.unique); the colon data correspond under the stalk isomorphism ofg'(Ideal.map_colon_pow_of_bijective), the exponent — the generic order ofJalong the centre throughf a'— transports because the order along a centre is read on stalks (ordAlongIdeal_pullbackDiffeomorph) and the connected component of the centre is carried by the homeomorphismg(genericOrdAlong_pullbackDiffeomorph); when no ideal sheaf with the colon stalks exists on one side, none exists on the other, and both sides are the unit ideal. The same argument asweakTransform_comap_liftStepofHironaka/Manifold/Sequence/Functor/, across the models. - The reduced transform: the closed sets
f⁻¹(E) ∪ f⁻¹(D)correspond underg'; the vanishing stalks are carried by the stalk isomorphism (vanishingStalk_preimage_pullbackDiffeomorph, the two-model form ofvanishingStalk_preimage_of_isLocalDiffeomorphAt'ofHironaka/Resolution/Analytic/IdealSheaf/VanishingPreimage.lean); the local-generator condition transports both ways — forward byhasLocalGenerators_pullback, back by the forward direction alongg⁻¹(gis a bijection). The same argument asreducedTransform_comap_of_surjective. IsAnalyticIsoOver: the local inverses are conjugated byg,g'(PartialDiffeomorph.trans); the bijection onto the set is read through the square.IsProperMap:f' = g⁻¹ ∘ f ∘ g'with homeomorphisms.
The Jacobian ideal and the monoidal transformations along a square, which need charts, are in
Hironaka/Resolution/Analytic/ModelTransport/SquareChart.lean.
A germ at h b vanishes on Z iff its pull-back along the local analytic isomorphism h
vanishes on h⁻¹(Z) at b: the two-model form of
Germ.vanishesOn_compTendsto_of_isLocalDiffeomorphAt'
(Hironaka/Resolution/Analytic/IdealSheaf/VanishingPreimage.lean), the same proof with the models
free.
The vanishing stalk of h⁻¹(Z) at b is the image of the vanishing stalk of Z at h b
under the germ map: the two-model form of vanishingStalk_preimage_of_isLocalDiffeomorphAt'.
The vanishing stalk along an analytic isomorphism across the models.
Local generators of the vanishing stalks of a set are carried along g
(hasLocalGenerators_pullback).
Local generators of the vanishing stalks, both ways (g is a bijection: the other way is the
forward direction along g⁻¹).
The order along a centre along g: the stalk isomorphism preserves inclusions and powers.
The generic order along a centre along g: the connected component of the centre through the
point is carried by the homeomorphism g (Homeomorph.image_connectedComponentIn), the order
pointwise.
The pointwise form of the square f ∘ g' = g ∘ f': f' = g⁻¹ ∘ f ∘ g'.
The reversed square, for g⁻¹, g'⁻¹.
The colon stalks (IsDivExceptional) along a square: the stalk isomorphism carries colon ideals
and powers (Ideal.map_colon_pow_of_bijective), the exponent (the generic order along the centre)
transports by genericOrdAlong_pullbackDiffeomorph.
Hironaka's weak transform [Hir64, p. 142] along a square of analytic isomorphisms across the
models: both sides are the unique ideal sheaf with the colon stalks (IsDivExceptional.unique),
the colon data corresponding under g'; when no such sheaf exists on one side none exists on the
other (pull back along g'⁻¹), and both are the unit ideal.
Hironaka's red(f⁻¹(E) ∪ f⁻¹(D)) [Hir64, Main Theorem II'(N) (iii), p. 156] along a
square: the closed sets correspond, the vanishing stalks along the stalk isomorphisms, the
local-generator condition both ways.
A local analytic isomorphism on a set transports along a square: the local inverse is
conjugated by the two isomorphisms (PartialDiffeomorph.trans).
A bijection onto a set transports along a square.
IsAnalyticIsoOver along a square: both directions by the forward lemmas at the square and
at the reversed square.
Properness along a square: f' = g⁻¹ ∘ f ∘ g' with g, g' homeomorphisms
(Homeomorph.isProperMap, IsProperMap.comp).