The padding identity of a datum at the coproduct #
The padding comparison at the level of a whole datum: Kollár's commutation of the functor with
closed embeddings, j^* B(X, I_X, E) = B(Y, I_Y, E|_Y) [Kol07, 34.4], read at the coproduct slice
(compare [Wlo09, §7.1]). A local embedding datum D padded along a coordinate embedding
σ : Fin n ↪ Fin n′ (padAlongData: every piece embedding padded by PieceEmbedding.padAlong σ)
has the coproduct local resolution, labels and members of D — read over the padded reading opens
Wp and the reading opens they carry along the slice (padPreimageOpens):
- the statement:
padAlongData,padPreimageOpens,isCompact_closure_padPreimageOpens,PadIdentityOn— an order isomorphismoof the label sets, an isomorphismψof the coproduct local resolutions withcomap ψ (members (o σp)) = members⁺ σpfor every label, and on every piece an isomorphism over the piece; - the cast leg with an order isomorphism:
BlowUpSequence.exists_diffeomorph_last_of_pullback_bijective_iso(list level) andBEDanFamStar.exists_diffeomorph_last_of_cast_iso(functor level), with an order ISOMORPHISM of the label sets: a diffeomorphism pulls back no empty centre, so the erasure of empty blow-ups is the identity (eraseEmpty_pullback_of_surjective) and the last-stage map ispullbackLiftLastDiffeomorphOfBijective; - the coproduct slice
S* := ⋃ᵢ sigmaMk⁺ i '' padSlice σ Gᵢ(sigmaPadSlice,isClosedSubmanifold_sigmaPadSlice);sigmaPadSliceDiffeomorph: the datum's coproduct ambient IS the slice, across the modelsFin nandFin (n′ − (n′ − n))(the sigma of the per-piecepadExtDiffeomorphfollowed bysigmaSubmanifoldDiffeomorphofHironaka/Resolution/Analytic/Kol07Thm45/SigmaSubmanifold.lean), withinclusionMap_sigmaPadSliceDiffeomorph;pullback_inclusionMap_sigmaPadSlice: the padded ideal restricted to the slice is the datum's ideal transported (IdealSheaf.ext_of_comap_sigmaMk,pullback_inclusionMap_padIdealper piece), andidealSheaf_sigmaPadSlice_le;preimage_sigmaPadSliceDiffeomorph_preimageOpens_ambImage: the datum's reading open is the trace of the padded one on the slice; the restricted slice mappadRestrictMap : N|U → N⁺|U⁺(incl_{S*} ∘ Φon the reading opens), analytic (contMDiff_padRestrictMap), withI|U = m^*(I⁺|U⁺)(restrictOpens_eq_pullback_padRestrictMap); - THE CORE
exists_padIdentityCore:bed.closedEmbeddingat(S*, I⁺, J*)makes the padded run the push-forward of the slice run ([Kol07, 34.4]; [Wlo09, Theorem 2.0.2(4)]),exists_closedSubmanifold_last_pushforwardRestrict_boundary(LocalResolutionPad.lean) gives the carried sliceS*_r,G₁, the ideal identity, the composite square and the order isomorphismo₁with the trace identity; the cast leg at(Φ, I, J*)givesG₀andε₀; theno := o₁.symm.trans ε₀.symm,ψ := inv (homOfPullbackEq (incl_{S*_r} ∘ (G₁ ∘ G₀)))(the two isomorphisms ofexists_isIso_localResolution_padAlong), the member identity in EQUALITY form for every label from the ideal-level trace identity (pullback_idealSheaf_inclusionMap_comp_of_hasSncWithProper, the cast helper atG₀) through the generic member transport, andψover the ambients in MORPHISM form —localResolutionMapOn⁺ ∘ ψ⁻¹ = homOfPullbackEq (padRestrictMap) ∘ localResolutionMapOn(the generic quotient square); - the data exposed as definitions by choice from the core —
padIdentityOrderIso(o),padIdentityIso(ψ) — withpadIdentityIso_isIso,comap_padIdentityIso_sigmaMembers,localResolutionMapOn_comp_inv_padIdentityIsoand its point formlocalResolutionMapOn_inv_padIdentityIso_apply, and the ASSEMBLYpadIdentityOn_of_forall_piece: the padding identity from the core and the piece clause stated against the NAMEDψ(CoproductPadIdentityPiece.leanproves that clause).
Nothing here is new mathematics: the argument is the padding leg of the comparison of two
embeddings (LocalResolutionPad.lean) at the coproduct slice, with an order isomorphism where the
piece case had an embedding. The generic homOfPullbackEq tools live in
HomOfPullbackEqCalculus.lean.
The cast leg with an order ISOMORPHISM (a diffeomorphism erases no centre) #
The list-level cast leg, for the plain pull-back along a BIJECTIVE local isomorphism: the
last-stage diffeomorphism is pullbackLiftLastDiffeomorphOfBijective, the strict transforms
correspond (strictTransformSubspaceSeq_last_pullbackLiftLast), and the last boundary families
correspond through an order ISOMORPHISM (totalTransformSeqFrom_last_pullbackLiftLast at the
empty family, exists_orderIso_of_eq).
The functor-level cast leg, with an order ISOMORPHISM of the label sets: along a
DIFFEOMORPHISM g (a surjective local isomorphism) the pulled-back list has no empty centre
(noEmptyCenters_pullback_of_surjective), so the erasure of empty blow-ups in the functor's value
is the identity (eraseEmpty_pullback_of_surjective) and the list-level leg applies.
The datum padded along a coordinate embedding — every piece embedding padded by
PieceEmbedding.padAlong σ; padLeftData/padRightData (CoproductSumData.lean) are its
instances by rfl.
Equations
- One or more equations did not get rendered due to their size.
Instances For
The reading opens of the datum carried by the padded reading opens along the slice
(preimageOpens (padExt σ G)).
Equations
- D.padPreimageOpens σ Wp i = Manifold.preimageOpens (Hironaka.Manifold.padExt σ (D.embedding i).G) ⋯ (Wp i)
Instances For
The reading opens read back through the padding slice are relatively compact
(isCompact_closure_preimage_padExt).
The padding identity of a datum at the coproduct ([Kol07, 34.4] at the coproduct slice):
an order isomorphism of the padded datum's label set onto the datum's (the padded run
is the run of the coproduct slice, stage by stage), an isomorphism of the coproduct local
resolutions carrying the datum's member of label o σp to the padded datum's member of label σp,
restricting on every piece to an isomorphism of the piece's local resolutions over the piece.
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- One or more equations did not get rendered due to their size.
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The coproduct slice of the padding and its identification with the datum's ambient #
The coproduct slice S* = ⋃ᵢ sigmaMk⁺ i '' padSlice σ Gᵢ inside the padded coproduct
ambient.
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- One or more equations did not get rendered due to their size.
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It is a closed submanifold of codimension n′ − n (isClosedSubmanifold_sigmaUnion at the pad
slices, isClosedSubmanifold_padSlice).
The datum's coproduct ambient IS the coproduct slice — across models (Fin n against
Fin (n′ − (n′ − n))): the sigma of the per-piece padExtDiffeomorph followed by
sigmaSubmanifoldDiffeomorph.
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- One or more equations did not get rendered due to their size.
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On points: incl_{S*} (Φ (sigmaMk i x)) = sigmaMk⁺ i (padExt σ Gᵢ x).
The slice ideal is the datum's ideal transported: the padded coproduct
ideal restricted to the coproduct slice is D.sigmaTriple.I pulled back along Φ⁻¹
(IdealSheaf.ext_of_comap_sigmaMk, pullback_inclusionMap_padIdeal per piece).
The slice lies in the zero set of the padded coproduct ideal (the hypothesis hSI of the
push-forward; idealSheaf_padSlice_le_padIdeal per piece).
The datum's reading open is the trace of the padded one on the slice: Φ⁻¹(S* ∩ U⁺) = U for
U⁺ = ambImage Wp, U = ambImage (padPreimageOpens σ Wp) (inclusionMap_sigmaPadSliceDiffeomorph,
coe_sigmaCoordImage, preimage_sigmaMk_iUnion_image).
The restricted slice map U → U⁺ #
The restricted slice map m : N|U → N⁺|U⁺, incl_{S*} ∘ Φ on the reading opens (lands in
U⁺ by preimage_sigmaPadSliceDiffeomorph_preimageOpens_ambImage).
Equations
- D.padRestrictMap σ Wp p = ⟨⋯.inclusionMap ((D.sigmaPadSliceDiffeomorph σ) ↑p), ⋯⟩
Instances For
It lies over incl_{S*} ∘ Φ (definitional).
It is analytic (ChartedSpace.liftPropWithinAt_subtypeVal_comp_iff, as
AnalyticMap.restrictMap).
The restricted ideals correspond along it: I|U = m^*(I⁺|U⁺)
(pullback_inclusionMap_sigmaPadSlice and pullback_symm_pullback, then pullback_pullback
along the inclusions).
The core: the order isomorphism and the isomorphism of the coproduct local resolutions #
The padding identity at the coproduct, its data ([Kol07, 34.4] at the coproduct slice): an
order isomorphism of the label sets and an isomorphism ψ of the coproduct local resolutions
carrying the datum's member of label o σp to the padded datum's member of label σp, and lying
over the ambients — the padded coproduct's map to its closed subspace, after ψ⁻¹, is the datum's
map followed by the slice identification. The argument: bed.closedEmbedding at (S*, I⁺, J*),
exists_closedSubmanifold_last_pushforwardRestrict_boundary (the carried slice S*_r, G₁, the
ideal identity, the composite square, the order isomorphism o₁), the cast leg at (Φ, I, J*)
(G₀, ε₀), ψ := inv (homOfPullbackEq (incl_{S*_r} ∘ (G₀.trans G₁))), the member identity from
pullback_idealSheaf_inclusionMap_comp_of_hasSncWithProper in equality form.
The data exposed: o and ψ by choice from the core, with their clauses; the assembly #
The order isomorphism of the label sets o : ι⁺ ≃o ι, chosen from the core
exists_padIdentityCore (the padded run is the run of the coproduct slice, stage by stage).
Equations
- D.padIdentityOrderIso σ Wp hWp bed hbed = ⋯.choose
Instances For
The isomorphism ψ of the coproduct local resolutions, chosen from the core
exists_padIdentityCore; the piece clause (CoproductPadIdentityPiece.lean) is stated against
this NAMED ψ.
Equations
- D.padIdentityIso σ Wp hWp bed hbed = ⋯.choose
Instances For
ψ is an isomorphism (ψ = inv (homOfPullbackEq (incl_{S*_r} ∘ (G₁ ∘ G₀))), the inverse of an
isomorphism).
The members correspond, in equality form for EVERY label: ψ carries the datum's member
of label o σp to the padded datum's member of label σp (the ideal-level trace identity
pullback_idealSheaf_inclusionMap_comp_of_hasSncWithProper along incl_{S*_r} ∘ G₁, the cast
helper at G₀, the generic member transport).
ψ lies over the ambients, in MORPHISM form: the padded coproduct's map to its restricted
closed subspace, after ψ⁻¹, is the datum's
map followed by the closed-subspace morphism over the restricted slice map padRestrictMap : N|U → N⁺|U⁺ (incl_{S*} ∘ Φ on the reading opens) — the generic quotient square along incl_{S*_r} ∘ (G₁ ∘ G₀) and padRestrictMap.
ψ lies over the ambients, in POINT form (the corollary of the morphism form through
toFun_homOfPullbackEq_val and inclusion_padRestrictMap): on points,
localResolutionMapOn⁺ (ψ⁻¹ z) lies over incl_{S*} (Φ (localResolutionMapOn z)) in the padded
coproduct ambient.
The padding identity from its core and the piece clause: given, on every piece i, an
isomorphism ψᵢ over the piece with resIn⁺ i ≫ ψ = ψᵢ ≫ resIn i for the NAMED
ψ = padIdentityIso (the piece clause, CoproductPadIdentityPiece.lean),
D.PadIdentityOn σ Wp hWp bed hbed holds with the data o, ψ and their clauses.