On the Nielsen realization problem, preliminaries.- Tori, crystallographic groups and the realization of mapping classes.- Marked Riemann surfaces and Fuchsian groups and Fenchel's realization theorem.- The Nielsen construction of finite groups of mapping classes.- On the Nielsen realization problem.- On finite groups of mapping classes of 3-manifolds: Some applications.

On the Nielsen realization problem, preliminaries.- Tori, crystallographic groups and the realization of mapping classes.- Marked Riemann surfaces and Fuchsian groups and Fenchel's realization theorem.- The Nielsen construction of finite groups of mapping classes.- On the Nielsen realization problem.- On finite groups of mapping classes of 3-manifolds: Some applications.