Left-right arrow in Einstein equation

[etotheipi]

Short, probably stupid, question; what does this left-right arrow $a \leftrightarrow b$ at the bottom-right mean? [It's this paper for ref.]

Does it just mean the last term repeated, except this time with $a$ and $b$ indices exchanged? Thanks.

 

[anuttarasammyak]

LHS is symmetric as for a nd b so RHS is also. So your thought seems reasonable.

 

[Demystifier]

Why is this thread on the Last week's most popular topics list?