I'm trying to find conditions for an endomorphism $L:TM\rightarrow TM$ verfying the condition
$$ \oint_{j,k,l} \left(\mathcal{T}_L\right)_{jm}^i \left(\mathcal{T}_L\right)_{kl}^m = \left(\mathcal{T}_L\right)_{jm}^i \left(\mathcal{T}_L\right)_{kl}^m + \left(\mathcal{T}_L\right)_{km}^i \left(\mathcal{T}_L\right)_{lj}^m + \left(\mathcal{T}_L\right)_{lm}^i \left(\mathcal{T}_L\right)_{jk}^m= 0, $$
where $\mathcal{T}_L$ denotes the Nijenhuis torsion of $L$ and a sum over $m$ is understood.
Assuming dim$(M)=3$$\mbox{dim}\,(M)=3$,the system should have $n^3(n-1)/2 =_{n=3} 27 $ (independent) equations. So, there is a compact way (maybe the Table
command mixed with DSolve
) to write the 27 equations quickly in Mathematica
? And does the programmprogram help me and will it solve symbolicalysymbolically the system giving the endomorphism $L$ in function of some real parameters?
Thanks :)
Pd: The Nijenhuis torsion of $L$ is written in terms of $L_j^i$ and $\frac{\partial L_j^i}{\partial x^k}$, such as show eq. 5 https://arxiv.org/pdf/1405.5118.pdf
EDIT:
Following the @bills' advice, I have decided try with an easier example. Let $f(x,y)=\sin(x+y)$. Then, is very easy check the identity
$$ f(x,y) + \frac{\partial^2f}{\partial x\partial y} =0 . $$
I have introduced this partial differential equation in Mathematica
using DSolve
:
DSolve[f[x, y] + D[D[f[x, y], y], x] == 0, f, {x, y}]
and hoping for a condition about the function $f$, but the program returns the same code.
At this point, what (or where) is the problem? Is a syntax problem? Or maybe is because the function DSolve can not be used to get conditions about a function from a differential equation? Then, it is there some command in Mathematica
which could do it?