Check if datagraph node 'v' forms an epsilon clique with
all elements in Nodes(V)
note: star ghost is considered having epsilon links with any vertex
(including itself)
note: since Nodes(V) already forms a clique, we just have to check
that v is epsilon connected to each element
tell if datanode v is a star (*)
note: there are different ways to detect '*'
the quickest for now is that '*' is (should be)
the only colorless datanode