In
graph theory, a
flow network (also known as a
transportation network) is a
directed graph where each edge has a
capacity and each edge receives a flow. The amount of flow on an edge cannot exceed the capacity of the edge. Often in
operations research, a directed graph is called a
network. The vertices are called
nodes and the edges are called
arcs. A flow must satisfy the restriction that the amount of flow into a node equals the amount of flow out of it, unless it is a
source, which has only outgoing flow, or
sink, which has only incoming flow. A network can be used to model traffic in a road system, circulation with demands, fluids in pipes, currents in an electrical circuit, or anything similar in which something travels through a network of nodes.