Uncovering overlapping community structures by the key bi-community and intimate degree in bipartite networks

•Introduce the key bi-communities, the free-nodes and the intimate degree IND.•Propose the algorithm 1 and the algorithm 2 for detecting the community structures in the bipartite networks.•Find overlapping vertices.•Give excellent experimental results.

Although many successful algorithms have been designed to discover community structures in network, most of them are dedicated to disjoint and non-overlapping communities. Very few of them are intended to discover overlapping communities, particularly the detection of such communities have hardly been explored in the bipartite networks. In this paper, a novel algorithm is proposed to detect overlapping community structures in bipartite networks. After analyzing the topological properties in bipartite networks, the key bi-communities and free-nodes are introduced. Firstly, some key bi-communities and free-nodes are extracted from the original bipartite networks. Then the free-nodes are allocated into a certain key bi-community by some given rules. In addition, the proposed algorithm successfully finds overlapping vertices between communities. Experimental results using some real-world networks data show that the performance of the proposed algorithm is satisfactory.