In Neu Theory, openings are always plural, examples:
- Two openings (one hole) are the transitions connecting the two surfaces (the “wall”) of the shell shape. Example: Consider a door as the hole between two rooms (two topological shells). When the door is closed, each room is a hollow with a complete concave surface. When the door (two openings) is open, the two hollow surfaces become connected as one topological shell.
- Two or more openings are the transitions connecting two or more parts of the same surface, Example: Punching a hole through a ball of dough shaping a donut.