The rainbow arborescence conjecture posits that if the arcs of a directed graph with $n$ vertices are colored by $n-1$ colors such that each color class forms a spanning arborescence, then there is a spanning arborescence that contains exactly one arc of every color. We prove that the conjecture is true if the underlying undirected graph is a cycle.
翻译:彩虹树形图猜想提出:若一个有向图具有 $n$ 个顶点,其弧被 $n-1$ 种颜色着色,且每种颜色类均构成一个生成树形图,则存在一个生成树形图,其中恰好包含每种颜色的一个弧。我们证明当底层无向图是一个环时,该猜想成立。