Digraph analogues for the Nine Dragon Tree Conjecture

Hui Gao, Daqing Yang

The fractional arboricity of a digraph $D$, denoted by $\gamma (D)$, is defined as $\gamma (D)={\max }_{H\subseteq D,|V(H)|>1}\frac{|A(H)|}{|V(H)|-1}$. Frank in [Covering branching, Acta S…