Interaction picture in QFT and Haag's theorem

We will discuss on interaction picture in quantum field theory and how Haag's theorem proves that this approach cannot be used to describe interacting fields. To do so, a brief introduction on algebraic quantum field theory is necessary. More or less, the main topics we will see are: C*-algebra, GNS theorem, Fock and Non-Fock representation, locality, Weyl representation, Haag's theorem