Gap 8: For a log-quadratic f = exp(a₀ + b·v + c₀|v|²), the Landau flux vanishes. This follows because ∇log f(v) - ∇log f(w) = 2c₀(v-w), so the flux is proportional to A(v-w)(v-w) = 0 by Lemma 3 (projection annihilation). Reference: Key step in the proof of Theorem 5 (thm:nullspace_sufficiency).
Maxwellians are in the nullspace of the Landau operator: Q(f,f) = 0. The flux A(v-w)[f(w)∇f(v) - f(v)∇f(w)] vanishes pointwise (because ∇log f is affine, so the score difference is proportional to v-w, which is annihilated by A(v-w)), making the integral and its divergence zero.
Gap 11: D(f) = 0 implies f is a Maxwellian. Chains: D=0 → parallelism (Lemma 6) → ∇log f affine (Lemma 7) → log f quadratic (Lemma 8) → f = exp(quadratic) → c₀ < 0 (L¹ integrability). Reference: Proof of Theorem 4 (thm:nullspace_necessity) + Corollary 2.