# Show that $R(\partial_i,\partial_j)h_{kp}=0$.

In picture below, I am not sure why $$R(\partial_i,\partial_j)h_{kp}=0$$. I think it is because we can consider $$h_{kp}$$ as a function. Am I right ?

The picture below is from 57th page of this paper.

• Can you also link the reference?
– user99914
Nov 20, 2015 at 8:43
• @JohnMa Sorry , I miss it .I have added it . Nov 20, 2015 at 9:27
• Yes, you are right, in that formula $h_{kl}$ is really a function so the second derivative commutes.
– user99914
Nov 20, 2015 at 11:31
• @JohnMa Thanks. Nov 20, 2015 at 11:37