| # Incidence matrix of a network Mathematically speaking, a network is a graph of nodes connected by directed arcs. Here, we assume that arcs are ordered pairs, with at most one arc joining any two nodes; we also assume that there are no self-loops (arcs from a node to itself). We do not assume that the edges of the graph are weighted — they are all similar. We can fully describe the network with the so-called arc-node incidence matrix, which is the matrix defined as
| The figure shows the graph associated with the arc-node incidence matrix
See also: Network flow.