Extended charts in smooth manifolds #
In a C^n
manifold with corners with the model I
on (E, H)
, the charts take values in the
model space H
. However, we also need to use extended charts taking values in the model vector
space E
. These extended charts are not PartialHomeomorph
as the target is not open in E
in general, but we can still register them as PartialEquiv
.
Main definitions #
PartialHomeomorph.extend
: compose a partial homeomorphism intoH
with the modelI
, to obtain aPartialEquiv
intoE
. Extended charts are an example of this.extChartAt I x
: the extended chart atx
, obtained by composing thechartAt H x
withI
. Since the target is in general not open, this is not a partial homeomorphism in general, but we register them asPartialEquiv
s.
Main results #
contDiffOn_extend_coord_change
: iff
andf'
lie in the maximal atlas onM
,f.extend I โ (f'.extend I).symm
is continuous on its sourcecontDiffOn_ext_coord_change
: forx x : M
, the coordinate change(extChartAt I x').symm โซ extChartAt I x
is continuous on its sourceManifold.locallyCompact_of_finiteDimensional
: a finite-dimensional manifold modelled on a locally compact field (such as โ, โ or thep
-adic numbers) is locally compactLocallyCompactSpace.of_locallyCompact_manifold
: a locally compact manifold must be modelled on a locally compact space.FiniteDimensional.of_locallyCompact_manifold
: a locally compact manifolds must be modelled on a finite-dimensional space
Given a chart f
on a manifold with corners, f.extend I
is the extended chart to the model
vector space.
Equations
- f.extend I = f.trans I.toPartialEquiv
Instances For
Variant of f.extend_left_inv I
, stated in terms of images.
If y โ f.target
and I y โ interior (range I)
,
then I y
is an interior point of (I โ f).target
.
If s โ f.source
and g x โ f'.source
whenever x โ s
, then g
is continuous on s
if and
only if g
written in charts f.extend I
and f'.extend I'
is continuous on f.extend I '' s
.
Technical lemma ensuring that the preimage under an extended chart of a neighborhood of a point in the source is a neighborhood of the preimage, within a set.
Technical lemma to rewrite suitably the preimage of an intersection under an extended chart, to bring it into a convenient form to apply derivative lemmas.
The preferred extended chart on a manifold with corners around a point x
, from a neighborhood
of x
to the model vector space.
Equations
- extChartAt I x = (chartAt H x).extend I
Instances For
Alias of extChartAt_target_union_compl_range_mem_nhds_of_mem
.
If we're boundaryless, extChartAt
has open target
If we're boundaryless, (extChartAt I x).target
is a neighborhood of the key point
If we're boundaryless, (extChartAt I x).target
is a neighborhood of any of its points
Around the image of a point in the source, the neighborhoods are the same
within (extChartAt I x).target
and within range I
.
Around a point in the target, the neighborhoods are the same within (extChartAt I x).target
and within range I
.
Around the image of the base point, the neighborhoods are the same
within (extChartAt I x).target
and within range I
.
Around the image of a point in the source, (extChartAt I x).target
and range I
coincide locally.
Around a point in the target, (extChartAt I x).target
and range I
coincide locally.
Around the image of the base point, (extChartAt I x).target
and range I
coincide locally.
Technical lemma ensuring that the preimage under an extended chart of a neighborhood of a point in the source is a neighborhood of the preimage, within a set.
Technical lemma ensuring that the preimage under an extended chart of a neighborhood of the base point is a neighborhood of the preimage, within a set.
Technical lemma ensuring that the preimage under an extended chart of a neighborhood of a point is a neighborhood of the preimage.
Technical lemma to rewrite suitably the preimage of an intersection under an extended chart, to bring it into a convenient form to apply derivative lemmas.
We use the name ext_coord_change
for (extChartAt I x').symm โซ extChartAt I x
.
Conjugating a function to write it in the preferred charts around x
.
The manifold derivative of f
will just be the derivative of this conjugated function.
Equations
- writtenInExtChartAt I I' x f = โ(extChartAt I' (f x)) โ f โ โ(extChartAt I x).symm
Instances For
In the case of the manifold structure on a vector space, the extended charts are just the identity.
A finite-dimensional manifold modelled on a locally compact field
(such as โ, โ or the p
-adic numbers) is locally compact.
A locally compact manifold must be modelled on a locally compact space.
Riesz's theorem applied to manifolds: a locally compact manifolds must be modelled on a
finite-dimensional space. This is the converse to Manifold.locallyCompact_of_finiteDimensional
.