“…Previous studies describe formulations on undirected graphs using edge variables only, in which the use of binary edge variables automatically excludes two‐node cycles (i.e., cycles with a depot and a client) unless suitable modifications are performed. In particular, use a variable , defined as binary for every pair to indicate whether the edge between clients i and j is used in the solution, and defined as {0,1,2} for every pair , indicating, respectively, whether the edge linking depot d and client i is not used or if it is used once or twice, with the latter case forming a two‐node cycle. The edge variables in can be related with the directed variables through the equalities for every edge .…”