πr topologies
The πr Whitney (or strong) topology is a topology
assigned to the space πr(M,N) of mappings from
a πr manifold
M to a πr manifold N having
r continuous
derivatives
. It gives a notion of proximity
of two πr mappings, and it allows us to speak of βrobustnessβ
of properties of a mapping. For example, the
property of being an embedding
is robust: if f:MβN
is a πr embedding, then there is a strong πr
neighborhood of f in which any πr mapping g:MβN
is an embedding.
Given a locally finite atlas {(Ui,Οi):iβI} and compact sets
KiβUi such that there are charts
{(Vi,Οi):iβI} of N for which
f(Ki)βVi for all iβI, and given a sequence
{Ο΅i>0:iβI}, we define the basic neighborhood
π°r(f,Ο,Ο,{Ki:iβI},{Ο΅i:iβI}) |
as the set of Cr mappings g:MβN such that for all iβI we have g(Ki)βVi and
sup |
That is, those maps that are close to and have their first derivatives close to the respective first -th derivatives of , in local coordinates. It can be checked that the set of all such neighborhoods forms a basis for a topology, which we call the Whitney or strong topology of .
The weak topology, or compact-open topology, is defined
in the same fashion but instead of choosing
to be a locally finite atlas for ,
we require it to be an arbitrary finite family of charts
(possibly not covering ).
The space with the weak or strong topologies is denoted by and , respectively.
We have that is always metrizable (with a complete metric)
and separable. On the other hand, is not even first countable (thus, not metrizable) when is not compact; however, it is a Baire space
. When is compact, the weak and strong topologies coincide.
Title | topologies |
---|---|
Canonical name | mathcalCrTopologies |
Date of creation | 2013-03-22 14:08:27 |
Last modified on | 2013-03-22 14:08:27 |
Owner | Koro (127) |
Last modified by | Koro (127) |
Numerical id | 5 |
Author | Koro (127) |
Entry type | Definition |
Classification | msc 57R12 |
Synonym | Whitney topology |
Synonym | compact-open topology |
Synonym | weak topology |
Synonym | strong topology |
Related topic | ConjectureApproximationTheoremHoldsForWhitneyCrMNSpaces |
Related topic | ApproximationTheoremAppliedToWhitneyCrMNSpaces |