The resolution is a locally finite ambient blow-up composite #
Kollár's resolution functor is projective over every compact subset [Kol07, Theorem 45(4)];
Włodarczyk's res_{Y,M} factors locally into a sequence of blow-ups at smooth centres, the
factorization (∗) of [Wlo09, Theorem 2.0.2]. Here: over every relatively compact open V ⊆ X
the resolution map Π_X is the composite of a finite sequence of blow-ups of the disjoint union of
the pieces' ambients, restricted to strict transforms (clause (4) of exists_functorial_resolution,
ResolutionAssembly.lean). The steps: an exhaustion member Uₙ ⊇ closure V, the datum
Dₙ over Uₙ with its gluing Γₙ, the factorization of AmbientLift.lean at the SHRUNK family
Γₙ.W i ⊓ Aᵢ (Aᵢ the trace of Uₙ on the ambient — every open of a piece is the preimage of an
open of its ambient under the closed embedding ambientPoint), so that the pieces lie inside
Uₙ, and the transport ofIsoOver
(Hironaka/Resolution/Analytic/Kol07Thm45/AmbientFactorizationTransport.lean) along the exhaustion
glue's identification of the part of R(X) over Uₙ with resolutionOn Dₙ.
Not in the sources beyond the statements cited; bookkeeping.
Every open of the piece X|V is, through the closed embedding ambientPoint, the trace of an
open of the ambient Gᵢ (IsInducing.isOpen_iff).
Shrinking the ambient open to the trace of O shrinks the base open to O:
pieceDom i (W ⊓ A) = pieceDom i W ∩ O when embPreimage A = val ⁻¹' O.
The ambient blow-up factorization at any open V ⊆ U, with the pieces inside a prescribed
open O ⊇ V ([Kol07, Theorem 45(4)]): the factorization of the glued space's map at the gluing
datum with the shrunk family Γ.W i ⊓ Aᵢ (Aᵢ the trace of O), with the independence of the
local resolution as hind.
A relatively compact open lies in some member of the exhaustion
(IsCompact.elim_directed_cover on the increasing Uₙ).
The two spellings of the part of R(X) over Uₙ. Internal.
The part of the piece resolutionOn Dₙ over Uₙ is the whole piece (range_subset).
Internal.
The part of R(X) over Uₙ IS resolutionOn (D n) bed: the exhaustion glue's
partIso at Uₙ = dom n (the part of the piece over Uₙ is the whole piece, range_subset).
Equations
- One or more equations did not get rendered due to their size.
Instances For
It lies over X|Uₙ: Π_{Uₙ} ∘ e = des|Uₙ (the hypothesis hcomm of the transport
ofIsoOver).
Π_X is a locally finite ambient blow-up composite (clause (4) of
exists_functorial_resolution; [Kol07, Theorem 45(4)]; the local factorization (∗) of
[Wlo09, Theorem 2.0.2]), with the independence of the local resolution as hind: over every
relatively compact open V, the factorization of the glued space over the exhaustion member
Uₙ ⊇ closure V with its pieces inside Uₙ, transported along the part identification
(ofIsoOver).