Coherence is a structure: the minimal unit stabilizing the interplay of Including and Excluding, ensuring that equivalence holds coherently.
Equivalence is determined by how it relates something and not-something. Given this determination, it cannot not derive a dynamic of structure — the configuration that formalizes how the preceding acts and conditions cohere. Coherence is this structure: the minimal unit that stabilizes the interplay between Including and Excluding, ensuring that equivalence holds.
Coherence is the first structure in the derivation. Where acts (like Including and Excluding) are things that happen and conditions (like Inclusion and Exclusion) are things that hold, structures are configurations — ways of being organized. Coherence is the minimal configuration in which Including and Excluding work together rather than pulling apart.
Note that Including and Excluding are oppositional acts, but they are the same kind of act on the same structure. This is what Coherence ensures: that the opposition between including and excluding is stabilized rather than left in contradiction.
But Coherence leaves something undetermined: the dynamics by which it is sustained. It describes a configuration but provides no engine to maintain it. This undetermination forces the next step: Relating.