Exclusion is a condition: what something is not.
Excluding is an act — something excluding everything it is not. Exclusion is what that act establishes: the persistent condition of what something is not. Acts happen; conditions hold. Excluding does; Exclusion holds.
Exclusion is forced alongside Inclusion by the same determination: negation is determined by how it relates thing and equivalence, and this forces dynamics of relation — the conditions through which things stand to one another. Exclusion is the condition negation works with on the other side: the stable “what something is not.”
Paired with Inclusion. Neither condition has content without the other: “what something is” has no meaning apart from “what something is not,” and vice versa.