theorem levelEffect_links_solow {s₀ ψ δ τ : ℝ} : levelEffect s₀ ψ δ τ = steadyStateKY (investmentRate s₀ ψ τ) δ := by simp only [levelEffect, steadyStateKY]
thesis/CESProofs/Macro/GrowthTax.lean:144
Growth and Dynamic Tax Revenue (Layer 4-5 of Macro Extension)