https://mathoverflow.net/questions/325185/is-there-any-math-notation-for-be-denoted-by
The sentence s "In many supervised learning problems one has an output variable $y$ and a vector of input variables $x$ described via a joint probability distribution $P(x,y)$" from wiki
Here s implicitly declares 3 notations $\{x,y,P(x,y)\}$.
So I wonder if there is a math notation appeared in any famous book so that I can explicitly declare some notation in handwriting notes and plaintext digital notes
For example, if we can use @, then s equals to "In many supervised learning problems one has an output variable @ $y$ and a vector of input variables @ $x$ described via a joint probability distribution @ $P(x,y)$", in my personal notebook it's very handy and clear.
And I think notation := cannot be used in sentence s.