Context
Color agreement is exactly the Boolean-policy rule that overlapping signatures may coexist only when they carry the same letter.
Proof or evidence
Every selector is covered exactly once, choosing its signature on or off. Knuth's color purification accepts the chosen on-options exactly when all overlaps agree in letter.
Verification notes
All 16,384 subsets of the fourteen signatures formed by two letters and all nonempty supports on three participants satisfy XCC consistency iff they are pairwise policy-compatible.
Limitations
- The compilation enumerates compatible signature families; expression-specific target intersections may still be empty.
- It does not claim polynomial total runtime when the solution family is exponential.
- Novelty is plausible but unconfirmed; no external review is recorded.