524.30 Openings

524.31 There are no surfaces. Therefore, there are no areas. So Euler’s topological aspects have to be altered to read: “Lines” = trajectories; “vertexes” = crossings; and “areas” = openings, i.e., where there are no trajectories or crossings.

524.32 When three or more “lines,” “vectors,” or trajectories each cross two others, we have an opening. Our definition of an opening is that it is surrounded, i.e., framed, by trajectories.

524.33 Every trajectory in a system will have to have at least two crossings. These are always as viewed, because the lines could be at different levels from other points of observation.