Lemma 102 in the compatible-family form: compatibility under restriction #
The values of BD_{n,m,j} on the relatively compact open subsets (BDanFam, BDFam.lean) form a
compatible family: for U ≤ V the value on U is the pull-back of the value on V along the open
inclusion with its empty blow-ups deleted (BDanFam_compat; the compatibility clause of
[Wlo09, Theorem 2.0.3 (4)] with [Wlo09, Definition 3.2.6], and the second clause of
[Kol07, 34.1] for the open embedding U ⊆ V). Both sides are cores over transported values
(coreFamOn_eq_coreOfListOf, coreOfListOf_pullback_eraseEmpty): the centres and the transforms
agree as sets, because the lift of U ⊆ V ⊆ M to the blowings-up is the composite of the lifts
(uniqueness of lifts, eq_of_comm_blowUp), and the transported values are the input family's
values at the traces U_S ≤ V_S, identified by the family's own compatibility and the behaviour
of the core over a sequence under pull-back (BDFamPullback.lean).
piOpen_mono,preimageOpens_piOpen_mono—π_{-1}^{-1}and the trace onS_0are monotone;liftStep_inclusion_eq_comp,transformSU_pullback_eq— the lifts compose, and the transform ofE^jpulls back to the transform of the restricted data;coreFamOn_compat,BDanFam_compat— the compatibility for the core on an open and for the value ofBD_{n,m,j}.
This is the compat field of the compatible family bdanFam in BOanFamOfInput.lean.
π_{-1}^{-1} is monotone on open sets.
The trace on S_0 of π_{-1}^{-1} is monotone on open sets.
The lift of the inclusion U ⊆ M to the blowings-up is the lift of V ⊆ M after the lift of
U ⊆ V (uniqueness of lifts, eq_of_comm_blowUp).
The transform of E^j pulled back along the lift of U ⊆ V is the transform of the data
restricted to U.
The core on an open is compatible under restriction: for U ≤ V the core on U is the
pull-back of the core on V along the open inclusion with its empty blow-ups deleted (the second
clause of [Kol07, 34.1]; [Wlo09, Theorem 2.0.3 (4)]). Both cores are cores over transported values
on the same centre and transform; the transported values agree because the input family is
compatible at the traces U_S ≤ V_S and the lift of U ⊆ M is the lift of V ⊆ M after the lift
of U ⊆ V.
The values of BD_{n,m,j} on the relatively compact open subsets are compatible under
restriction ([Wlo09, Theorem 2.0.3 (4)]; the second clause of [Kol07, 34.1]): for U ≤ V the value
on U is the pull-back of the value on V along the open inclusion with its empty blow-ups
deleted. This is coreFamOn_compat at the tuned triple.