def al_acyclic_graph_3():
    return Al([
        Vx(0, (2, 3)),
        Vx(1, 2),
        Vx(2, (3, 4)),
        Vx(3, (5, 6)),
        Vx(4, 7),
        Vx(5, 7),
        Vx(6),
        Vx(7)
    ])
def al_cyclic_graph_1():
    return Al([
        Vx(0, (2, 3)),
        Vx(1, 2),
        Vx(2, (3, 4)),
        Vx(3, (5, 6)),
        Vx(4, 7),
        Vx(5, 7),
        Vx(6, 8),
        Vx(7),
        Vx(8, 2)
    ])
def al_acyclic_graph_1():
    return Al([
        Vx(0, (1, 2)),
        Vx(1, (4, 5)),
        Vx(2, (6, 7)),
        Vx(3, 7),
        Vx(4),
        Vx(5, 8),
        Vx(6, 8),
        Vx(7),
        Vx(8)
    ])
def al_acyclic_graph_2():
    return Al([
        Vx(0, (1, 2)),
        Vx(1, (4, 5)),
        Vx(2, (6, 7, 9)),
        Vx(3, 7),
        Vx(4),
        Vx(5, 8),
        Vx(6, 8),
        Vx(7, 9),
        Vx(8, 9),
        Vx(9),
        Vx(10, 2)
    ])
def al_acyclic_graph_4():
    return Al([
        Vx(0, (1, 2, 5)),
        Vx(1, (3, 4, 5)),
        Vx(2, 6),
        Vx(3, 7),
        Vx(4, 7),
        Vx(5, 8),
        Vx(6, 8),
        Vx(7, 9),
        Vx(8, 9),
        Vx(9),
        Vx(10, 12),
        Vx(11, 12),
        Vx(12, (6, 13)),
        Vx(13)
    ])
def al_acyclic_graph_5():
    return Al([
        Vx(0, 4),
        Vx(1, 5),
        Vx(2, (6, 7)),
        Vx(3, 7),
        Vx(4, 11),
        Vx(5, 11),
        Vx(6, 11),
        Vx(7, 8),
        Vx(8, (9, 10)),
        Vx(9),
        Vx(10),
        Vx(11, (12, 13, 14)),
        Vx(12),
        Vx(13),
        Vx(14)
    ])
def al_cyclic_graph_2():
    return Al([Vx(0, (1, 2, 3)), Vx(1, 4), Vx(2, 4), Vx(3, 2), Vx(4, 3)])