Visit of Professor Arendt

Oct. 2019: Professor Wolfgang Arendt visited Isabelle Chalendar (LAMA). In a joint work with I. Chalendar and B. Celaries entitled « In Koenigs’ footsteps: diagonalization of composition operators », a complete description of the spectrum of the composition operator C’ on the Frechet space of holomorphic functions on the open unit disc is given. The second research paper of W. Arendt is a joint work with I. Chalendar and R. Eymard, entitled « Universal Galerkin approximation, essential coercivity and applications to nite elements ».