Rainbow triangles and the Caccetta‐Häggkvist conjecture
Rainbow triangles and the Caccetta‐Häggkvist conjecture
Abstract A famous conjecture of Caccetta and Häggkvist is that in a digraph on vertices and minimum outdegree at least n / r there is a directed cycle of length or less. We consider the following generalization: in an undirected graph on vertices, any collection of disjoint sets of edges, …