Bartosz Milewski on Nostr: Yes, I'm also used to up/down summation-- I had to force myself to lower them all ...Yes, I'm also used to up/down summation-- I had to force myself to lower them all ;-). A quick check for this formula is to realize that both sides must be anti-symmetric in free indices, and that \(\epsilon_{1 2 3}\}\) is equal to one.