Thus, the loss calculation technique of the Covington dynamic oracle is not directly applicable to the 2-Planar parser.
if we statically choose a canonical plane assignment and we calculate loss with respect to that assignment (i.e., creating a correct arc in the non-canonical plane incurs loss), then the Covington technique, based on counting individually unreachable arcs and then correcting for the presence of cycles, works for the 2-Planar parser.