Assembly of a biological reaction network is based on graph theory: 43 a network is a mathematical representation of pairwise relationships between objects. In a network 𝐺, vertices 𝑉 representing the objects are connected by edges 𝐸. In the case of edges with orientations pointing to one end of the vertices, the graph is defined as a directed graph. The mathematical representation of an undirected graph 𝐺 with 𝑚 vertices and 𝑛 edges is shown in Eq. 1 and Eq. 2: