Nothing refers to the bottom concept (empty set). It describes concepts that cannot have any individuals. It is used for specifying restrictions on the roles.


Those examples show how to use the keyword nothing.

Example: The role of parent is irreflexive.
Nothing is-parent-of itself.
Example: Two sentences below are equivalent.
Nothing is-part-of at-least two things.
Every-single-thing is-part-of at-most one thing.
Example: A more complex restriction on roles.
Nothing is a dead-body that has-inside a living-thing.