Rank properties of the arc-node incidence matrix

Recall the definition of the arc-node incidence matrix of a network.

A number of topological properties of a network with m nodes and n edges can be inferred from those of its node-arc incidence matrix A, and of the reduced incidence matrix tilde{A}, which is obtained from A by removing its last row. For example, the network is said to be connected if there is a path joining any two nodes. It can be shown that the network is connected if and only if the rank of tilde{A} is equal to m-1.

See also: Nullspace of a transpose incidence matrix.