“…The exponents β jk induce an unordered simple graph on the set of vertices V = {1, 2, 3, 4, 5, 8} by putting an edge between j and k whenever β jk = 0. Because β 12 , β 13 ≥ 1, β 14 ≥ 1, β 56 ≥ 1, β 57 ≥ 1 and β 58 ≥ 1, there are edges connecting the pairs of vertices (1, 2), (1,3), (1,4), (5,6), (5,7) and (5,8). Condition (5.10) means that the degree of each vertex is at least 2.…”