  The acknowledged model for networks of collaborations is the hypergraph
model. Nonetheless when it comes to be visualized hypergraphs are transformed
into simple graphs. Very often, the transformation is made by clique expansion
of the hyperedges resulting in a loss of information for the user and in
artificially more complex graphs due to the high number of edges represented.
The extra-node representation gives substantial improvement in the
visualisation of hypergraphs and in the retrieval of information. This paper
aims at showing qualitatively and quantitatively how the extra-node
representation can improve the visualisation of hypergraphs without loss of
information.
