A community network consisting of 20 nodes in 3 communities. The top, bottom-left, and bottom-right are the first, the second, and the third communities, respectively. The outer coupling matrix B is defined as: if nodes i and j (j ≠ i) are connected by a solid line, then b_ij = 0.001; if nodes i and j (j ≠ i) are connected by a dashed line, then b_ij = −0.001.