  With the proliferation of mobile technology and IT development, people can
use social network services at any place and anytime. Among many social network
mining problems, identifying cohesive subgraphs attract many attentions from
different fields due to its numerous applications. Among many cohesive subgraph
models, k-core is the most widely used model due to its simple and intuitive
structure. In this paper, we formulate (p,n)-core in signed networks by
extending k-core. (p,n)-core simultaneously guarantees sufficient internal
positive edges and deficient internal negative edges. We formally prove that
finding an exact (p,n)-core is NP-hard. Hence, we propose three efficient and
effective algorithms to find a solution. Using real-world and synthetic
networks, we demonstrate the superiority of our proposed algorithms.
