  Network science has proved useful in analyzing structure and dynamics of
social networks in several areas. This paper aims at analyzing the
relationships of characters in the sitcom Friends. In particular, two important
aspects are investigated. First, how are the structure of the communities.
Second, not only static structure of the graphs and causality relationships are
investigated, but also temporal aspects. Also, this sitcom is frequently
associated with distinguishing facts such as: all six characters are equally
prominent; it has no dominant storyline; and friendship as surrogate family.
This paper uses tools from network theory to check whether these and other
assumptions can be quantified and proved correct. The main findings regarding
the centrality and temporal aspects are: patterns in graphs representing
different time slices of the show change; overall, degrees of the six friends
are indeed nearly the same; however, in different situations (thus graphs), the
magnitudes of degree centrality do change; betweenness centrality differs
significantly for each character thus some characters are better connectors
than others; there is a high difference regarding degrees of the six friends
versus the rest of the characters, which points to a centralized network; there
are strong indications that the six friends are part of a surrogate family. As
for the presence of groups within the network, methods of different natures
were investigated aiming at detecting groups (communities) in networks
representing different time slices as well as the network of all episodes. Such
methods were compared (pairwise and also using various metrics, including
plausibility). The multilevel method performs reasonably in general. Also, it
stands out that those methods do not agree very much, resulting in groups that
are very different from method to method.
