Counting the ideals of given codimension of the algebra of Laurent polynomials in two variables

Christian Kassel, Christophe Reutenauer

We establish an explicit formula for the number $C_n(q)$ of ideals of codimension $n$ of the algebra ${\mathbb{F}}_q[x,y,x^{-1},y^{-1}]$ of Laurent polynomials in two variables ove…