hot to put poset and subposet and order_filter and order_ideal in one graph,but different color?
PP = Posets(6)[18];show(PP,vertex_size=100,vertex_colors='yellow');
Q = PP.subposet([2,4]);Q;show(Q,vertex_size=100,vertex_colors='green')
PP.order_filter([3,2]);PP.order_ideal([4,3])