  We here present a method of clearly identifying multi-partite subgraphs in a
network. The method is based on a recently introduced concept of the
communicability, which very clearly identifies communities in a complex
network. We here show that, while the communicability at a positive temperature
is useful in identifying communities, the communicability at a negative
temperature is useful in idenfitying multi-partitite subgraphs; the latter
quantity between two nodes is positive when the two nodes belong to the same
subgraph and is negative when not. The method is able to discover `almost'
multi-partite structures, where inter-community connections vastly outweigh
intracommunity connections. We illustrate the relevance of this work to
real-life food web and protein-protein interaction networks.
