  The data gathered in all kind of web-based systems, which enable users to
interact with each other, provides an opportunity to extract social networks
that consist of people and relationships between them. The emerging structures
are very complex due to the number and type of discovered connections. In
webbased systems, the characteristic element of each interaction between users
is that there is always an object that serves as a communication medium. This
can be e.g. an email sent from one user to another or post at the forum
authored by one user and commented by others. Based on these objects and
activities that users perform towards them, different kinds of relationships
can be identified and extracted. Additional challenge arises from the fact that
hierarchies can exist between objects, e.g. a forum consists of one or more
groups of topics, and each of them contains topics that finally include posts.
In this paper, we propose a new method for creation of multi-layered social
network based on the data about users activities towards different types of
objects between which the hierarchy exists. Due to the flattening,
preprocessing procedure new layers and new relationships in the multi-layered
social network can be identified and analysed.
