private lemma quotient_rule_variance_eq (a b c : ℝ) (hc : c ≠ 0) : (a * c - b * b) / c ^ 2 = a / c - (b / c) ^ 2 := by field_simp
thesis/CESProofs/Foundations/InformationGeometry.lean:777
The VRI σ² = T·χ is fundamentally an exponential family identity: