For the meaning, you just have to retrace back to where the things were defined, just like in programming. I am a mathematician, and I do not understand anything in the linked screenshot either (other than big O notation, which many people here should actually know!). FWIW, the author’s preference for Greek letters is rather excessive for my personal taste.

The Greek characters in the screenshot are standard for the subject. The letters "chi" and "psi" (in that order) are the preferred letters for denoting Dirichlet characters, and zeros of L-functions are always denoted by "rho."

See, this is what I meant. Not only reading in the paper where X was defined but have this in-depth knowledge of why a certain symbol was used and how it came to be, knowledge that probably not even all full-time mathematicians that studied their entire life have.

I see, this makes sense. Probably gets easier when one gets used to it.

Unless they're deeply ingrained in the literature I find preferences for curly letters quite irritating (especially some older typefaces), dyslexic or not I genuinely cannot read them sometimes; it's a big blocker on my productivity.

I sometimes rewrite them using A, B, C then try to understand them. This procedure should be automatic but unfortunately TeX is ancient.

Ok, but there is a difference between looking up definitions and understanding something.

Agree, same in programming, you could see that f = (a,b) => a ^ (10+ b) , but not understand what it actually means and why 10 is there and not 9.

Another example is the use of commonly known constants, such as pi, i or e. No paper will define those constants and explain indepth what they mean, so you need prior knowledge or to find external resources. I think for such complex papers you will find many such cases where extensive prior knowledge is needed.

Maybe because you haven't tried to understand it?

Can't be harder than learning the meaning behind these characters: https://www.pandatree.com/book/DiaryofWorm.jpg

I don't mean the symbols themselves, but how each member was defined and the history behind it.

It's like watching a Marvel movie and not only knowing the plot of the current movie but also the deep history of each character and their relationships with other characters.

I assume the paper didn't come out of nowhere and it's based on "the shoulders of giants".

Pretty sure it's much harder than Chinese. The depth and abstraction of the concepts involved and the density of these concepts in these lines vastly eclipses anything in any natural language

It would take a long path to understand it.. and the path would need to be filled with good resources.

I'm sure 3b1b will make an explanation video :)

I mean I got as far as things like the square root symbol and power-of, I've scanned the comment section and links and there's still little to nothing I understand, lol. Something with prime numbers.