Resumen de Sur la structure du groupe d' automorphismes de certaines surfaces affines

Stéphane Lamy

• We describe the structure of the group of algebraic automorphisms of the following surfaces 1) P1 k ×P1 k minus a diagonal; 2) P1 k ×P 1 k minus a fiber. The motivation is to get a new proof of two theorems proven respectively by L. Makar-Limanov and H. Nagao. We also discuss the structure of the semi-group of polynomial proper maps from C2 to C2.