In this paper, we investigate asymptotically periodic functions from the
point of view of operator algebra and dynamical systems. To study the
M\"{o}bius disjointness of these functions, we prove a general result on the
averages of multiplicative functions in short arithmetic progressions. As an
application, we show that Sarnak's M\"{o}bius Disjointness Conjecture holds for
certain topological dynamical systems.Comment: 46 page