DIAG-11 · Diagnosis · Invariant — holds by construction, no expiry
Subset counts cannot invert
The law
Under one consistent counting rule, a defined subset's count cannot exceed its superset's over identical scope and window; any inversion is a counting fault, not behavior. Absent a shared rule, a nonzero cross-system gap alone proves nothing.
Scope
Verify the subset relation is definitional before alerting, conversions-per-click, view-through, and cross-device pairs are NOT subsets. Both counts must be exact (unsampled, unmodeled).
What this licenses you to do
Hard-alert on any inversion of an exact definitional subset pair inside one counting system; across unlinked systems, alert only on breaks in a source's historical gap ratio, never on the gap existing.