| I will describe some recent results about the ring of algebraic cycles mod. algebraic equivalence on the Jacobian JC of a curve C . Thisring is quite large, and seems to be very difficult to study. I propose toconsider the "tautological subring" obtained by applying natural operations (sum, intersection product, multiplication by integers...) starting from the class of C in JC. This ring turns out to be finitely generated and to have avery interesting structure. |