Let's say I have an expression like $\,a^{I}=2b^{I}+3c^{I}$ where $I$ stands for an arbitrarily large set of indices. It's known that $\,\frac{\partial a^K}{\partial c^{L}}=3\,\delta^K_L$ (equals a product of Kronecker deltas) but, how can I do that in Mathematica using packages like XAct, Xpert and any else related to XTensor.
(i) How could I achieve that?.
(ii) Also, notice that I asumed that $\,b \neq b(c)$, how can I tell Mathematica to do so when computing the partial derivative?.