Note on the bijectivity of the Pak-Stanley labelling

This article has the sole purpose of presenting a simple, self-contained and direct proof of the fact that the Pak-Stanley labeling is a bijection. The construction behind the proof is subsumed in a forthcoming paper [R. Duarte and A. Guedes de Oliveira, The braid and the Shi arrangements and the Pak-Stanley labeling, Eur. J. Combinatorics, in press.], but an actual self-contained proof is not explicitly included in that paper.