[lostmyoldone]

I don't really know, I'm not an expert in the field. What I do know, is that I can usually get almost anything written in English in a statistics text, but when it goes mathematical notation I really struggle even with the simplest of concepts.

Type theory is a little like that, at least from some authors that - although the are is well suited for symbols - kind of goes a little off the rails using seven different kind of arrows and all the symbols in at least three different alphabets, instead of maybe just write covariant, or even an abbreviated form adjecent to the arrow?