The vanishing stalk of a preimage along a local analytic isomorphism, for charted types #
vanishingStalk_preimage_of_isLocalDiffeomorphAt of
Hironaka/Resolution/Analytic/Functor/PullbackTransport.lean is stated for bundled analytic
manifolds and an AnalyticMap; here the same statements are proved for a bare analytic map
between charted types ([IsManifold π(π, E) Ο M] alone, no Hausdorff or second-countability
assumptions): a germ vanishes on hβ»ΒΉ(Z) at b iff its push-forward along the local inverse
vanishes on Z at h b (Germ.vanishesOn_compTendsto_of_isLocalDiffeomorphAt'), and
vanishingStalk (h β»ΒΉ' Z) b = Ideal.map (germMap h hh b) (vanishingStalk Z (h b))
(vanishingStalk_preimage_of_isLocalDiffeomorphAt', through the bijective germ map
germMap_bijective_of_isLocalDiffeomorphAt). The proofs are those of the bundled lemmas. Off the
centre of a blowing-up the map is a local analytic isomorphism (condition (1) of
[BM88, Definition 4.1]) and the strict transforms are the preimages of the components, so the
vanishing stalks upstairs are transports of the vanishing stalks downstairs; this is used in the
Jacobian bookkeeping of the Hironaka library (Hironaka/Resolution/Analytic/BM97/LedgerStep.lean,
Hironaka/Resolution/Analytic/ModelTransport/Square.lean).
A germ at h b vanishes on Z iff its pull-back along the local analytic isomorphism h
vanishes on hβ»ΒΉ(Z) at b (the charted-type form of
Germ.vanishesOn_compTendsto_of_isLocalDiffeomorphAt): near b the map h agrees with a partial
diffeomorphism Ξ¦, which carries π[h β»ΒΉ' Z] b onto π[Z] (h b).
The vanishing stalk of hβ»ΒΉ(Z) at b is the image of the vanishing stalk of Z at h b
under the germ map of the local analytic isomorphism h at b (the charted-type form of
vanishingStalk_preimage_of_isLocalDiffeomorphAt, for a bare analytic map between charted types):
the comap of the vanishing stalk of the preimage is the vanishing stalk of Z (the germ identity
above), and Ideal.map of a comap along a surjection is the ideal itself
(germMap_bijective_of_isLocalDiffeomorphAt).