The conclusion of Włodarczyk's Claim descends along the local cover of Theorem 105 #
[Kol07, Theorem 105] evaluates BO_{n,1} on a triple T through a local cover
g : T'.X.left → T.X.left (a coproduct of open immersions, surjective) on whose pieces a smooth
hypersurface of maximal contact exists: BO(T') = g^* BO(T), since the functor commutes with smooth
morphisms ([Kol07, Theorem 103 (2)], commutesWithSmooth). The conclusion of Włodarczyk's Claim in
the proof of [Wlo05, Theorem 4.7.1] (ClaimFor,
Hironaka.Resolution.Algebraic.Wlo05.EmbeddedClaimAt) for the run on T at a point p of the
strict transform c̃_i follows from the conclusion for the pulled-back run on T' at a point q
over p, for the member c' := I_{closure η'} of a suitable point η' over η (a component of
g⁻¹(V(c)) through the image of q, coe_support_strictTransformSeq_biUnion): the first
containing stage is the same on both sides (the lifted generic points correspond,
GenericLift.uniq), and the stalk identity descends along the stalk isomorphism of the stage lift
(openImmersionCoprods_pullbackStageHom). The commutation with smooth morphisms is [Kol07, 34.1].
The same bookkeeping, with the chain-relative conclusion, is cp1For_of_pullback_cover
(Hironaka.Resolution.Algebraic.Wlo05.EmbeddedCP1Cover).
The stop rule through the lifted generic point #
When the strict transform at stage l is the reduced ideal of the closure of ζ, the centre
at l contains it iff ζ lies on the centre.
The centre of the pulled-back sequence at l, in the mk form of the indices.
The stage lift applied to a point, followed by the stage map: the image of the pulled-back stage map.
The conclusion of Włodarczyk's Claim descends along a coproduct of open immersions
([Kol07, Theorem 105]): if it holds for the pulled-back run on T' at every point η' over η
that is a generic point of g⁻¹(V(c)) (with the member I_{closure η'}), it holds for the run
on T at η.