Reverse Polish notation is a form of post-fix notation which is different to the normal INFIX notation that we are taught to use in school. Like boolean mathematics, this was actually invented long before computer scientists used it as it is apparently easier to solve and work with complex mathematical models. Computer scientists quickly adopted this form of arithmetic to use at a low level in programming, to convert higher-level human INFIX arithmetic to more computer friendly post-fix notation.

Backus-naur form

https://www.slideshare.net/grahamwell/bakus-naur-form

Reflections...

Which part of the front-end analysis stage do these elements belong to?

1. Lexical analysis
2. Syntax diagram
3. Semantic analysis
4. Intermediate code generation?