theorem underdamped_iff {r ω : ℝ} (hω : 0 < ω) : dampingRatio r ω < 1 ↔ r < ω := by simp only [dampingRatio] exact div_lt_one hω
thesis/CESProofs/Dynamics/MultiplierCycles.lean:248
Multiplier-Cycle Duality in a Multi-Sector Economy