Polynomial theory underpins a vast array of problems in modern combinatorics, providing tools to encode, manipulate and extract information from sequences and discrete structures. Central to this area ...

Joyal’s proof was published here: André Joyal, Une théorie combinatoire des séries formelles. Advances in Mathematics 42 (1981), 1–82. (I try not to link to Elsevier, as I’m permanently furious with ...