$\mathfrak{sl}_3$-web bases, intermediate crystal bases and categorification

Abstract

We give an explicit graded cellular basis of the $\mathfrak{sl}_3$-web algebra $K_S$. In order to do this, we identify Kuperberg's basis for the $\mathfrak{sl}_3$-web space $W_S$ with a version of Leclerc-Toffin's intermediate crystal basis and we identify Brundan, Kleshchev and Wang's degree of tableaux with the weight of flows on webs and the $q$-degree of foams. We use these observations to give a "foamy" version of Hu and Mathas graded cellular basis of the cyclotomic Hecke algebra which turns out to be a graded cellular basis of the $\mathfrak{sl}_3$-web algebra. We restrict ourselves to the $\mathfrak{sl}_3$ case over $\mathbb{C}$ here, but our approach should, up to the combinatorics of $\mathfrak{sl}_N$-webs, work for all $N>1$ or over $\mathbb{Z}$.