V.D271 — Deceleration Parameter q₀

Deceleration parameter: q₀ = Ω_m/2 − Ω_Λ = 0.3151/2 − 0.6849 = −0.527. Negative value confirms accelerating expansion, consistent with SN Ia observations. Matches Planck-ΛCDM q₀ = −0.527 to <0.1%.