- #1
andresB
- 626
- 374
Some words before the question.
For two smooth manifolds [itex]M[/itex] and [itex]P[/itex] It is true that
[tex]T(M\times P)\simeq TM\times TP [/tex]
If I have local coordinates [itex]\lambda[/itex] on [itex]M[/itex] and [itex]q[/itex] on [itex]P[/itex] then ([itex]\lambda[/itex], [itex]q[/itex]) are local coordinates on [itex]M\times P[/itex] (right?). This means that in these local coordinates the tanget vectors are of the form [itex]a^{i}\frac{\partial}{\partial\lambda^{i}}+b^{i}\frac{\partial}{\partial q^{i}}[/itex]
Now, I can compute push forwards in local coordinates. For example, for a function
[tex]f(\lambda, q)\rightarrow(\lambda,Q(q,\lambda))[/tex]
Then
[tex]f^{*}\left(\frac{\partial}{\partial\lambda}\right)=\frac{\partial}{\partial\lambda}+\frac{\partial Q}{\partial\lambda}\frac{\partial}{\partial q}[/tex]
where I just had to do the matrix product of the Jacobian to the column vector [itex](1,0)^{T}[/itex].
Actual Question.
For a function [itex]f:\, TM\times TP\longrightarrow TM\times TP[/itex]
and without using local coordinates what can be said about the Push forward [itex]f^{*}:\, TM\times TP\longrightarrow TM\times TP[/itex] ?.
Particularly interested if the push forward can be descomposed into something in [itex]TM[/itex] product something in [itex]TP[/itex].
For two smooth manifolds [itex]M[/itex] and [itex]P[/itex] It is true that
[tex]T(M\times P)\simeq TM\times TP [/tex]
If I have local coordinates [itex]\lambda[/itex] on [itex]M[/itex] and [itex]q[/itex] on [itex]P[/itex] then ([itex]\lambda[/itex], [itex]q[/itex]) are local coordinates on [itex]M\times P[/itex] (right?). This means that in these local coordinates the tanget vectors are of the form [itex]a^{i}\frac{\partial}{\partial\lambda^{i}}+b^{i}\frac{\partial}{\partial q^{i}}[/itex]
Now, I can compute push forwards in local coordinates. For example, for a function
[tex]f(\lambda, q)\rightarrow(\lambda,Q(q,\lambda))[/tex]
Then
[tex]f^{*}\left(\frac{\partial}{\partial\lambda}\right)=\frac{\partial}{\partial\lambda}+\frac{\partial Q}{\partial\lambda}\frac{\partial}{\partial q}[/tex]
where I just had to do the matrix product of the Jacobian to the column vector [itex](1,0)^{T}[/itex].
Actual Question.
For a function [itex]f:\, TM\times TP\longrightarrow TM\times TP[/itex]
and without using local coordinates what can be said about the Push forward [itex]f^{*}:\, TM\times TP\longrightarrow TM\times TP[/itex] ?.
Particularly interested if the push forward can be descomposed into something in [itex]TM[/itex] product something in [itex]TP[/itex].