Compatible families of finite successions over the compact subsets #
Włodarczyk's compatible-family form of principalization Wlo09, Theorem 2.0.3; Definition 3.2.6;
Theorem 3.5.1 (2), the form in which Hironaka's Main Theorem II''(N) and the real-analytic
principalization theorem are stated: a proper analytic map M̃ → M which over an open
neighbourhood of every compact set is a finite composite of blow-ups with smooth centres,
compatibly across compacts. Włodarczyk's principalization is "locally but not globally a sequence
of blow-ups at smooth centers" [Wlo09, Introduction]: over a neighbourhood U of a compact set Z
the morphism splits into a finite sequence of blow-ups U = U_0 ← U_1 ← ⋯ ← U_r with smooth
centres C_{i-1} ⊆ U_{i-1}, and for Z_1 ⊆ Z_2 with U_1 ⊆ U_2 the restriction of the sequence
over U_2 to U_1 "determines" the sequence over U_1 — it is an extension of it in the sense of
[Wlo09, Definition 3.2.6]: the same blow-ups with isomorphisms (blow-ups with empty centre)
interspersed.
FiniteSuccession.restrict S h: the restriction of a succession overU_2to an openU_1 ≤ U_2(stages the preimages ofU_1, centres and maps restricted; a blow-up restricted to an open subset is the blow-up of the restricted centre), andFiniteSuccession.IsExtensionOf T S, Włodarczyk's "Tis an extension ofS".FiniteSuccession.Hom R S φ: a morphism of successions overφ : N → M, an index map from the stages ofSto those ofRwith maps between the stages overφ, compatible with the blow-downs; the two relations below are such morphisms with conditions on the maps and centres.FiniteSuccession.IsPullbackUpToEmptyAlong R S g: for a local analytic isomorphismg : N → M, the successionRover an open ofNis the pull-back of the successionSover an open ofMalongg, up to blow-ups with empty centre — the induced sequenceg^*(S)is an extension ofR, the form of [Wlo09, Theorem 3.5.1 (2)] in which the commutation of principalization with local analytic isomorphisms is stated.FiniteSuccession.IsPushforwardUpToEmptyAlong S R τ: for a closed embeddingτ : N → M, the successionSover an openUofMis the push-forward alongτof the successionRover an openU'ofNwithτ(U') ⊆ U, up to blow-ups whose centres lie outside the part overτ(U')— Kollár'sj_* B[Kol07, Definition 30.3], the form in which the commutation of principalization with closed embeddings [Kol07, 34.3] is stated over the compact sets.ExtensionCompatibleFamily M: Włodarczyk's data in [Wlo09, Theorem 2.0.3 (1), (4)] — a manifoldspace = M̃with an analytic mapmap : M̃ → M; for every compactK ⊆ M(Mathlib'sCompacts M) an open neighbourhoodnhd K ⊇ K, monotone inK, and a finite successionseq Kovernhd Kwhose end result is identified withmap⁻¹(nhd K)overnhd K(toSpace,map_toSpace,toSpace_isIso); and the compatibilityisExtensionOf_restrict: forK_1 ⊆ K_2the restriction ofseq K_2tonhd K_1is an extension ofseq K_1. The properness ofmapis a clause of the main theorems, not of the structure.ExtensionCompatibleFamily.IsPullbackAlong F' F gandExtensionCompatibleFamily.IsPushforwardAlong F F' τ: the two relations between successions, over every pair of compactsK' ⊆ N,K ⊆ Mwhose neighbourhoods correspond under the map.
The restriction of a finite succession to an open subset #
A map into an open subset V of a manifold M' is analytic when it is analytic as a map into
M' (Mathlib's liftPropWithinAt_subtypeVal_comp_iff; the general-domain form of
contMDiff_codRestrict_opens).
The trace of U₁ on the stage U_i of S: the preimage of U₁ under the composite
blow-down σ^i : U_i → U₂ ⊆ M (Włodarczyk's restriction of the factorization to Ũ₁,
[Wlo09, Theorem 2.0.3 (4)]).
Equations
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The later stages of the restriction: the traces of U₁ on U_1, …, U_r.
Equations
- S.restrictOpensLater U₁ j = (S.stage j.succ).restrict (S.restrictStageOpens U₁ j.succ)
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The restricted blow-downs σ_{i+1}| between the traces: the first lands in U₁ itself, the
others between traces of later stages (a blowing-up restricted over an open subset).
Equations
- S.restrictOpensMapAux U₁ 0 hi = ⟨fun (q : ((M.restrict U₁).finStages (S.restrictOpensLater U₁) ⟨0 + 1, ⋯⟩).carrier) => ⟨↑((S.map ⟨0, hi⟩) ↑q), ⋯⟩, ⋯⟩
- S.restrictOpensMapAux U₁ i.succ hi = ⟨fun (q : ((M.restrict U₁).finStages (S.restrictOpensLater U₁) ⟨i + 1 + 1, ⋯⟩).carrier) => ⟨(S.map ⟨i + 1, hi⟩) ↑q, ⋯⟩, ⋯⟩
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The open inclusion U₁ → U₂ as an analytic map (Mathlib's Opens.inclusion with
contMDiff_inclusion), the stage-0 inclusion of the restriction.
Equations
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The restricted centres C_i ∩ σ^{-i}(U₁): the centre C_i comapped along the inclusion of
the trace (possibly empty: Włodarczyk's isomorphism steps,
[Wlo09, Definition 3.2.6, Remark (1)]).
Equations
- S.restrictOpensCenterAux h 0 hi = Manifold.IdealSheaf.pullback ⇑(AnalyticManifold.FiniteSuccession.restrictOpensIncl h) ⋯ (S.center ⟨0, hi⟩)
- S.restrictOpensCenterAux h i.succ hi = (S.center ⟨i + 1, hi⟩).restrict (S.restrictStageOpens U₁ ⟨i + 1, ⋯⟩)
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The trace of U₁ in U₂, as an open of the stage U_0 = U₂, is U₁: the canonical analytic
isomorphism ↥(val⁻¹' U₁) ≃ ↥U₁ (the stage-0 transport).
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- One or more equations did not get rendered due to their size.
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The inverse of the stage-0 transport as an analytic map U₁ → ↥(val⁻¹' U₁).
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Each restricted map is the monoidal transformation of the restricted centre: a blowing-up
restricted over an open subset is the blowing-up of the restricted centre
(IsBlowUp.restrictOpens'), with the trace lemmas for closed submanifolds and their ideal sheaves
(IsClosedSubmanifold.preimage_val, isIdealSheafOf_pullback_val); at stage 0 the statement is
transported along restrictTraceDiffeomorph (IsBlowUp.diffeomorph_comp,
IsClosedSubmanifold.preimage_of_isLocalDiffeomorph, comap_idealSheaf_of_isLocalDiffeomorph).
The restriction of a finite succession S over the open U₂ ⊆ M to an open U₁ ≤ U₂
(Włodarczyk's restriction of the factorization of prin_{I|Ũ_2} to Ũ_1,
[Wlo09, Theorem 2.0.3 (4)]): the stages are the preimages (σ^i)⁻¹(U₁) ⊆ U_i, the centres the
restrictions C_i ∩ (σ^i)⁻¹(U₁) (possibly empty: Włodarczyk's isomorphism steps,
[Wlo09, Definition 3.2.6, Remark (1)]), the maps the restrictions of the σ_{i+1} — a blow-up
restricted to an open subset is the blow-up of the open subset with the restricted centre, as is
immediate from the chart description of the blowing-up [BM88, Definition 4.1]
(IsBlowUp.restrictOpens').
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- One or more equations did not get rendered due to their size.
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Włodarczyk's extension relation #
The composite σ_{a+1} ∘ ⋯ ∘ σ_b : U_b → U_a of the maps of S between two stages a ≤ b
(Nat.leRecOn on a ≤ b; the identity at a = b, σ_{a+1} at b = a + 1; stageMap is the
case a = 0).
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- One or more equations did not get rendered due to their size.
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The centre C_a on the stage U_a, a < r, indexed by the stage.
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Włodarczyk's extension of a sequence of blow-ups [Wlo09, Definition 3.2.6]: T is an
extension of S when T is a sequence of blow-ups and isomorphisms
M = T_0 = ⋯ = T_{j_1-1} ← T_{j_1} = ⋯ = T_{j_2-1} ← ⋯ ← T_{j_m} = ⋯ = T_{m'} with T_{j_i} = S_i:
there are indices j_1 < ⋯ < j_m (m = S.length, m' = T.length) such that the blow-ups of T
at the indices j_i are those of S (the stages T_{j_i} identified with S_i over M,
compatibly with the maps and the centres) and every other step of T is an isomorphism, a
blow-up with empty centre. In the Lean: a block index blk : {0, …, m'} → {0, …, m} (the stage
T_k is identified with S_{blk k}; blk 0 = 0, blk m' = m, each step raises blk by 0 or
1, the steps raising it being the j_i), identifications e k : T_k ≃ S_{blk k} (Włodarczyk's
"=": analytic isomorphisms over M, i.e. commuting with the composite blow-downs, so that e 0
is the identity of M), compatible with the maps (σ^S_{blk k + 1} ∘ ⋯ ∘ σ^S_{blk (k+1)} ∘ e (k+1) = e k ∘ σ^T_{k+1}, through stageMapLE: at a jump the blow-up of S, at a non-jump the
identity) and with the centres (at a jump C^T_k is the pull-back of C^S_{blk k} along e k);
at a non-jump the step is an isomorphism, a blow-up with empty centre
[Wlo09, Definition 3.2.6, Remark (1)]. "The definition of extension arises naturally when we pass
to open subsets of the considered ambient manifold" (loc. cit.); [Wlo09, Theorem 3.5.1 (2)]
states the compatibility of the canonical resolution with local analytic isomorphisms in these
terms. That the restriction of a compatible family's succession is an extension of the
succession over the smaller compact is the content of ExtensionCompatibleFamily's last field,
not of this definition.
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- One or more equations did not get rendered due to their size.
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A morphism of finite successions over φ : N → M, from the finite succession R over an
open U' of N to the finite succession S over an open U of M. With r = S.length and
r' = R.length: an index j_k = blk k of a stage of R for every stage S_k, with j_0 = 0,
j_r = r' and each step of S raising the index by 0 or 1, and analytic maps
f_k : R_{j_k} → S_k (map k) lying over φ (σ^S_k ∘ f_k = φ ∘ σ^R_{j_k}, read in M through
the inclusions of U and U') and compatible with the blow-downs
(σ^S_{k+1} ∘ f_{k+1} = f_k ∘ σ^R_{j_k + 1} ∘ ⋯ ∘ σ^R_{j_{k+1}}, through stageMapLE). The
pull-back and the push-forward of successions (IsPullbackUpToEmptyAlong,
IsPushforwardUpToEmptyAlong) are morphisms with conditions on the maps and the centres.
The index
j_kof the stage ofRmapped to the stageS_k.- map (k : Fin (S.length + 1)) : ContMDiffMap (modelWithCornersSelf 𝕜 E') (modelWithCornersSelf 𝕜 E) (R.stage (self.blk k)).carrier (S.stage k).carrier ⊤
The map
f_k : R_{j_k} → S_k. j_0 = 0.j_r = r'.- blk_succ (k : Fin S.length) : ↑(self.blk k.succ) = ↑(self.blk k.castSucc) ∨ ↑(self.blk k.succ) = ↑(self.blk k.castSucc) + 1
Each step of
Sraises the index by0or1. - stageMap_map (k : Fin (S.length + 1)) (p : (R.stage (self.blk k)).carrier) : (M.inclusion U) ((S.stageMap k) ((self.map k) p)) = φ ((N.inclusion U') ((R.stageMap (self.blk k)) p))
f_klies overφ:σ^S_k ∘ f_k = φ ∘ σ^R_{j_k}, read inM. - map_map (k : Fin S.length) (hle : self.blk k.castSucc ≤ self.blk k.succ) (p : (R.stage (self.blk k.succ)).carrier) : (S.map k) ((self.map k.succ) p) = (self.map k.castSucc) ((R.stageMapLE hle) p)
The
f_kare compatible with the blow-downs.
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R, a finite succession over an open U' of N, is the pull-back of the finite succession
S over an open U of M along g : N → M, up to blow-ups with empty centre: there is a
morphism R → S over g (FiniteSuccession.Hom), with index j_k and maps f_k : R_{j_k} → S_k,
whose maps are local analytic isomorphisms, such that at a step raising the index the centre of
R is the pull-back f_k^*(C_k) of the centre of S and at a step that does not, the pull-back
of the centre is empty. So R is the sequence of the fibre products N ×_M S_k with some of its
blow-ups of empty centre (isomorphisms) removed.
Relation to the source.
- Translation.
R.IsPullbackUpToEmptyAlong S gis Włodarczyk's "the induced resolution $\varphi^*(M_{iZ_i})$ is an extension of the canonical resolution of $\varphi^*(M_Z, I, E, \mu)$" [Wlo09, Theorem 3.5.1 (2)], read for successions: the induced sequence $g^*(S)$, of the fibre products $N \times_M S_k$ Wlo09, Proposition 3.4.1; Definition 3.4.2, is an extension of $R$ in the sense of [Wlo09, Definition 3.2.6] (FiniteSuccession.IsExtensionOf). - Restatement. The fibre products $N \times_M S_k$ are not formed. The relation is stated through local analytic isomorphisms $f_k$ from the stages of $R$ to those of $S$, lying over $g$ (Włodarczyk's lifts $\varphi_k$ of [Wlo09, Proposition 3.4.1 (1)], read on the stages of $R$), compatible with the blow-downs, with the centre of $R$ the pulled-back centre at a step that raises the index and an empty pulled-back centre at the others. These data determine the stages of $R$ as the fibre products, because a blowing-up commutes with pull-back along a local analytic isomorphism and $f_0$ is the restriction of $g$.
Equations
- One or more equations did not get rendered due to their size.
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S, a finite succession over an open U of M, is the push-forward of the finite succession
R over an open U' of N along the closed embedding τ : N → M, up to blow-ups whose centres
lie outside the part over τ(U') — Kollár's j_* B [Kol07, Definition 30.3], with centres
Z_i^X := (j_i)_*(Z_i^S) and the natural inclusions j_i : S_i → X_i of the strict transforms of
τ(N), for a succession S over an open U ⊇ τ(U'): there is a morphism R → S over τ
(FiniteSuccession.Hom), with index j_k and maps f_k : R_{j_k} → S_k, whose maps are
embeddings with image closed in the part of S_k over τ(U'), such that at a step raising the
index the centre of R is the preimage f_k⁻¹(C_k) of the centre of S, at a step that does
not, f_k misses the centre, and every point of a centre of S lying over τ(U') is in the image
of f_k. So over τ(U') the centres of S are the images of the centres of R and the images
of the f_k are the strict transforms of τ(U'), and S is the push-forward of R with
blow-ups whose centres lie away from τ(U') interspersed.
Relation to the source.
- Translation.
S.IsPushforwardUpToEmptyAlong R τis Kollár's equation $B(X, I_X, E) = j_* B(Y, I_Y, E|_Y)$ for a closed embedding $j$ [Kol07, 34.3], read over the opens of two compatible families: $j_* B$ is the push-forward of [Kol07, Definition 30.3], whose centres are $Z_i^X := (j_i)_*(Z_i^S)$ for the natural inclusions $j_i \colon S_i \to X_i$ of the strict transforms. - Restatement. Kollár's equation compares sequences over one space. Here the succession over
the open $U$ of $M$ is compared with the succession over an open $U'$ of $N$ with
$\tau(U') \subseteq U$, so it is the push-forward up to the blow-ups whose centres lie outside
the part over $\tau(U')$ — the blow-ups of the sequence over $\tau^{-1}(U)$ that the sequence
over the smaller open $U'$ omits, as the pull-back relation
IsPullbackUpToEmptyAlongomits the blow-ups with empty pulled-back centre. - Restatement. The strict transforms $S_i$ and the inclusions $j_i$ are not formed. The relation is stated through embeddings $f_k$ from the stages of $R$, whose images are closed in the part over $\tau(U')$ and contain every centre point over $\tau(U')$, with the centre of $R$ the preimage of the centre of $S$ at a step raising the index and $f_k$ missing the centre at the others. These data determine $S$ over $\tau(U')$ as the push-forward: $f_0$ is the restriction of $\tau$, and the image of $f_{k+1}$ is the strict transform of the image of $f_k$ under a blow-up whose centre is the image of a centre of $R$, or misses the image.
Equations
- One or more equations did not get rendered due to their size.
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Compatible families of finite successions over the compact subsets #
Włodarczyk's data in [Wlo09, Theorem 2.0.3 (1), (4)] with [Wlo09, Definition 3.2.6], the
compatible-family form of the analytic main theorems: a manifold M̃ (space) with an analytic
map M̃ → M (map; Włodarczyk's prin_I, Hironaka's canonical modification X_γ → X); for every
compact K ⊆ M an open neighbourhood U_K = nhd K ⊇ K, monotone in K ("corresponding open
neighborhoods U_1 ⊂ U_2"), and a finite succession seq K of blow-ups with smooth centres over
U_K whose end result U_r is identified with Ũ = map⁻¹(U_K) over U_K (toSpace,
map_toSpace, toSpace_isIso: "U_r = Ũ", "the restriction prin_{I|Ũ} splits into" the
sequence); and the compatibility (4): for K_1 ⊆ K_2 the restriction of seq K_2 to U_{K_1} is
an extension of seq K_1 — "the restriction of the factorization of prin_{I|Ũ_2} to Ũ_1
determines the factorization of prin_{I|Ũ_1}". The properness of map is a clause of the main
theorems.
Relation to the source.
- Restatement. The compatibility of the identifications across compacts (over $U_{K_1}$,
toSpace K_2restricted to the end result of the restriction ofseq K_2istoSpace K_1after the identification of the end results given by the extension) is not a field because it is a theorem,ExtensionCompatibleFamily.toSpace_comp_restrictStageIncl_eq(Hironaka.Resolution.Analytic.Wlo09.FamilyCoherence): a map from the end result of a succession over $U_K$ to $\tilde M$ over $U_K$ is unique (ExtensionCompatibleFamily.eq_of_map_comp_eq).
- space : AnalyticManifold 𝕜 E
The manifold
M̃. - map : AnalyticMap self.space M
The analytic map
M̃ → M(Włodarczyk'sprin_I; Hironaka's canonical modificationX_γ → X[Hir64, p. 155]). For every compact
K ⊆ M, an open neighbourhoodU_KofK[Wlo09, Theorem 2.0.3 (1)].- subset_nhd (K : TopologicalSpace.Compacts M.carrier) : ↑K ⊆ ↑(self.nhd K)
K ⊆ U_K. K_1 ⊆ K_2givesU_{K_1} ⊆ U_{K_2}([Wlo09, Theorem 2.0.3 (4)]: "corresponding open neighborhoodsU_1 ⊂ U_2").- seq (K : TopologicalSpace.Compacts M.carrier) : (M.restrict (self.nhd K)).FiniteSuccession
The finite sequence of blow-ups over
U_K[Wlo09, Theorem 2.0.3 (1)]. - toSpace (K : TopologicalSpace.Compacts M.carrier) : AnalyticMap (self.seq K).last self.space
The identification of the end result
U_rof (∗) withŨ = map⁻¹(U_K): an analytic mapU_r → M̃… - map_toSpace (K : TopologicalSpace.Compacts M.carrier) : ContMDiffMap.comp self.map (self.toSpace K) = ContMDiffMap.comp (M.inclusion (self.nhd K)) (self.seq K).composite
- toSpace_isIso (K : TopologicalSpace.Compacts M.carrier) : (self.toSpace K).IsIsoOver (⇑self.map ⁻¹' ↑(self.nhd K))
… which is an analytic isomorphism onto
map⁻¹(U_K)("U_r = Ũ"). - isExtensionOf_restrict (K₁ K₂ : TopologicalSpace.Compacts M.carrier) (h : K₁ ≤ K₂) : ((self.seq K₂).restrict ⋯).IsExtensionOf (self.seq K₁)
[Wlo09, Theorem 2.0.3 (4)] with [Wlo09, Definition 3.2.6]: for
K_1 ⊆ K_2, the restriction of the sequence overU_{K_2}toU_{K_1}is an extension of the sequence overU_{K_1}.
Instances For
The compatible family F' over N is the pull-back of the compatible family F over M
along g : N → M: for compacts K' ⊆ N, K ⊆ M with g(U_{K'}) ⊆ U_K, the succession of F'
over U_{K'} is the pull-back along g of the succession of F over U_K, up to blow-ups with
empty centre (FiniteSuccession.IsPullbackUpToEmptyAlong, [Wlo09, Theorem 3.5.1 (2)]).
Equations
- One or more equations did not get rendered due to their size.
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The compatible family F over M is the push-forward of the compatible family F' over N
along τ : N → M: for compacts K' ⊆ N, K ⊆ M with τ(U_{K'}) ⊆ U_K, the succession of F
over U_K is the push-forward along τ of the succession of F' over U_{K'}, up to blow-ups
whose centres lie outside the part over τ(U_{K'}) (FiniteSuccession.IsPushforwardUpToEmptyAlong,
[Kol07, 34.3]).
Equations
- One or more equations did not get rendered due to their size.