Common root functions of two digraphs
Mao-cheng Cai · Journal of Graph Theory · 1989
Abstract Let D1 and D2 be finite digraphs, both with vertex set V, let a and b be given functions from V to Z+, and let k be a positive integer. In this paper we give a necessary and sufficient condition for the existence of k arc‐disjoint arborescences in each of D1 and D2 satisfying the condition that for each v in V magnified image a(v) 1(v) = r2(v) < b(v). Where ri(v) denotes the number of the arborescences in Di rooted at v, i = 1, 2.