“…where ⊕ α A [α] is the intra-layer adjacency matrix and ⊕ α,β A [α,β] is the inter-layer adjacency matrix corresponding to the connectivity matrix C. Figure 1 presents an example of a system with two layers; the physical layer contains two OT nodes (1,2) and the cyber layer comprises three IT nodes (3, 4, and 5). The intralayer adjacency matrices, corresponding to each layer as well as the intra-layer matrix, are defined by the matrices A [1] (4), A [2] (5), and ⊕ α A [α] (6). Similarly, the connectivity matrix between the layers is expressed by C (7), and it is obtained from the inter-layer adjacency matrices A [1,2] (8), where A [2,1] = A [1,2]T .…”