theorem
SimpleGraph.exists_orientation_of_average_degree_le
{V : Type u_1}
[Finite V]
{G : SimpleGraph V}
{d : ℕ}
(hGcolorable : G.Colorable 2)
(hGdeg : ∀ (s : Finset V), (induce (↑s) G).edgeSet.ncard ≤ d * s.card)
:
∃ (r : V → V → Prop), Irreflexive r ∧ Std.Asymm r
A bipartite simple graph whose induced subgraphs all have average degree at most 2 * d can be
oriented in such a way that all edges have outdegree at most d.