Descent of a blow-up sequence along a surjective local analytic isomorphism #
The descent of [Kol07, Proposition 37], (37.1)–(37.2), iterated along the sequence. On manifolds,
with the functors valued in centre lists: a list L' on N whose two pull-backs to a fibre
product (P, p₁, p₂) of the surjective local analytic isomorphism g : N → M with itself agree is
the pull-back of a unique list L on M, by recursion on L'. The first centre is saturated
(saturated_of_isFibreProduct), so it is the preimage of a closed submanifold Z of M
(IsClosedSubmanifold.image_of_saturated); the tail lives on the blowing-up of N along g⁻¹Z,
which is the domain of the lift g₁ : Bl_{g⁻¹Z} N → Bl_Z M; the lifted projections form again a
fibre product (isFibreProduct_lifted), and the tail descends by the recursive call. Uniqueness is
pullback_injective_of_surjective.
[Kol07, Proposition 37], (37.1)–(37.2) iterated ("we can repeat the above argument"): a list on
N whose two pull-backs to a fibre product of g with itself agree descends to M.
[Kol07, Proposition 37], the descent step with its uniqueness: a list on the
cover whose two pull-backs to the fibre product agree is the pull-back of exactly one list on the
base (uniqueness by pullback_injective_of_surjective).