N. Ilieva, H. Narnhofer A Fermi Field Algebra as Crossed Product (54K, LaTeX) ABSTRACT. On the example of Luttinger model and Schwinger model we consider the observable algebra of interacting fermi systems in two--dimensional space--time and construct field algebra related to it as a crossed product with some automorphism group. Fermi statistics results for conveniently chosen automorphisms. The extension of time evolution to the field algebra and its asymptotic behaviour are treated. For the Luttinger model time evolution is asymptotically anticommutative, while for the Schwinger model we find a reformulation of confinement.