digraph {

  P -> K2 [dir="back",style="dotted"]
  K2 -> K1
  K2 -> K3
  K3 -> BHn
  K3 -> X [color="invis"]
  K3 -> K4

  K1 [label="K1 (uncle)"]
  K2 [label="K2 (node)",color="red",fontcolor="red"]
  K3 [label="K3"]
  K4 [color="red",fontcolor="red"]

  X [color="invis",fontcolor="invis"]
  Y [color="invis",fontcolor="invis"]
  P [label="parent",color="gray",fontcolor="gray"]

  BHn [shape="box",label="black height n",style="dotted",fontname="Italic"]

  K1 -> BHn
  K1 -> Y [color="invis"]
  Y -> BHn [color="invis"]
  K1 -> BHn

  K4 -> BHn
  K4 -> BHn

}