Certain conference speakers need to be told that using sans-serif ∑ for one central notation and sans-serif bold ∑ for a different central notation is a bad idea. That decorating both of them by the same subscripts and the same hats doesn't help. And that when someone asks for clarification of the notation, answering with "We should move on...this is a thing you can compute on your own" rather than actually explaining is rude.

0xDE@11011110@mathstodon.xyz@gnivasch Ugh. I was going to say that at least they are visually farther apart than just applying boldface, but in the subscripts and superscripts it's not easy to tell the x's from the X's.