Let us prove following interesting identity between and
for any function .
For any function , using the formula
we obtain
Since is a funtion, we know that
then we obtain
Now is a vector, we need to use the Riemmanian curvature tensor, which measures the difference between and .
Notice that there was an extra term involving Lie bracket. Fortunately, that term vanishes. Thus
The proof follows.
I am wondering that why is a vector?
Comment by lucky — February 5, 2013 @ 20:14
Hi lucky, thanks for your comment, to be exact, I should say that is a vector field instead of . However, as components, we often use to denote the vector field since
Comment by Ngô Quốc Anh — February 5, 2013 @ 21:08
Hi Ngo!, To your knowledge,is there an analog relation between the Laplacian and the bi-Laplacian?
F
Comment by Fab — September 28, 2013 @ 23:13
Dear Fab,
I have not seen anything like that once. Fortunately, we can derive a similar formula by taking another to get
I hope this could help you a bit ;).
Comment by Ngô Quốc Anh — September 28, 2013 @ 23:19
Just a curiosity, how can I write down the bi-Laplacian on a manifold?
Comment by Fab — September 29, 2013 @ 21:28
Dear Fab,
I don’t think we have a very precise formula for in local coordinates so far as its calculation is quite complicated and possibly useless. Instead, you may use
to deal with.
Comment by Ngô Quốc Anh — September 29, 2013 @ 22:30