
Ancient Roots of BNF - willwinger
https://blogs.scientificamerican.com/roots-of-unity/a-feat-of-mathematical-eponymy/
======
watergatorman
Interesting article.

There is both left and right recursion in the definition of <number>, but this
EBNF (Wirth notation) uses iteration only:

number = digit { digit } [ "." digit { digit } ] .

