abstract: Let P be an irreducible monic polynomial in \(\mathbb{F}_q[T] =: A.\) With the help of his log-algebraicity theorem for the Carlitz module, G. Anderson has constructed a finitely generated A-module contained in the ring of integers of the \(P\)th cyclotomic function field and formulated a conjecture which is an analogue of the famous Vandiver conjecture. In this talk, we will explain the connexion between this module and Taelman’s class module, and, as a consequence, we will see that Anderson’s conjecture is false in general by producing an explicit contre-example. This talk is based on a joint work with Lenny Taelman.