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棵生成树形图,则必存在一棵生成树形图,其恰好包含每种颜色的弧各一条。我们证明当该有向图对应的无向基础图为环时,该猜想成立。