ABSTRACT
N etwork theory is one of the most fundamental and important sciences to help us discover and analyze existing complex systems such as so-
cial network, smart grid, biological networks and so on. In the past decades, research on networks has exploded in a wide range of areas. However, up until recently, most of research attention was given to an individual network in which all interactions are conducted in a single layer network, while neglecting that entities interact with each other can encompass multiple networks, and the interactions can also diffuse from one network to another. To better understand such complex systems, it is necessary to generalize traditional network system to a more complicated system in which multiple layers are taken into account.
