This is exactly the same concept of flow rates that we used for the edge weights in the directed graph for the Markov chain.

The set of values \\(H_{i,j}\\) is an "infinite square matrix." The values can be picked off right from the graph: \\(H_{i,j}\\) = the weight of the edge from \\(i\\) to \\(j\\) if it exists in the graph, else 0.

The weighted graph is a specification for the system of coefficients \\(\[H_{i,j} \]\\) that determine the master equation.