Problem A sequence d = (d1, d2, ..., dn) is graphic if there is a simple graph with degree sequence d. Prove that if d = (di, d2, ..., dn) is graphic and di > d2 > ... >dn then a) [h=1d; is even, and b) for 1 d2 > ... >dn then a) [h=1d; is even, and b) for 1