Robbins' theorem
Equivalence between strongly orientable graphs and bridgeless graphs / From Wikipedia, the free encyclopedia
This article is about Robbins' theorem in graph theory. For Robin's theorem in number theory, see divisor function.
In graph theory, Robbins' theorem, named after Herbert Robbins (1939), states that the graphs that have strong orientations are exactly the 2-edge-connected graphs. That is, it is possible to choose a direction for each edge of an undirected graph G, turning it into a directed graph that has a path from every vertex to every other vertex, if and only if G is connected and has no bridge.