theorem multiple_equilibria_fold {ρ κ : ℝ}
(hρ : ρ < 1) (hκ_pos : 0 < κ) (hκ_small : κ < (1 - ρ) / 4) :
∃ J_low J_high : ℝ,
1 ≤ J_low ∧ J_low ≤ 2 ∧ 2 ≤ J_high ∧
perCapitaSurplus J_low ρ = κ ∧ perCapitaSurplus J_high ρ = κ := by
obtain ⟨J_low, hJl1, hJl2, hJl_eq⟩ := multiple_equilibria_lower_root hρ hκ_pos hκ_small
obtain ⟨J_high, hJh2, hJh_eq⟩ := multiple_equilibria_upper_root hρ hκ_pos hκ_small
exact ⟨J_low, J_high, hJl1, hJl2, hJh2, hJl_eq, hJh_eq⟩Paper 1c, Section 3: The Participation Game