theorem detection_asymmetry [NeZero J] (hJ : 0 < J)
{ρ : ℝ} (hρ : ρ ≠ 0) {c : ℝ} (hc : 0 < c) :
-- (a) Aggregate is ρ-invariant at symmetry
powerMean J ρ hρ (symmetricPoint J c) = c ∧
-- (b) Fisher information is zero (information shadow)
fisherInfoRho (symmetricPoint J c) ρ = 0 ∧
-- (c) Gradient is orthogonal to 1⊥ (F insensitive to informative perturbations)
(∀ v : Fin J → ℝ, orthToOne J v →
∑ j : Fin J, (1 / (↑J : ℝ)) * v j = 0) ∧
-- (d) All log-ratios vanish at symmetry (no contrast signal)
(∀ j k : Fin J, logRatio (symmetricPoint J c) j k = 0) :=
⟨powerMean_symmetricPoint hJ hρ hc,
fisherInfoRho_zero_at_symmetry hc ρ,
fun v hv => gradient_orthogonal_to_onePerp v hv,
fun j k => logRatio_zero_at_symmetry c j k⟩CES Estimation Theory: Connecting Theory to Data