Degree complete graphs

Ryser [Combinatorial Mathematics, Carus Mathematical Monograph, vol. 14, Wiley, New York, 1963] introduced a partially ordered relation ‘≽≽’ on the nonnegative integral vectors. It is clear that if S=(s1,s2,…,sn)S=(s1,s2,…,sn) is an out-degree vector of an orientation of a graph G with vertices 1,2,…,n1,2,…,n, then equation(Π) View the MathML source