theorem
proved
cascade_implies_ESS
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IndisputableMonolith.GameTheory.CooperationCascade on GitHub at line 43.
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40def cascades (frac : ℝ) : Prop := cascadeThreshold ≤ frac
41
42/-- Cascade implies ESS. -/
43theorem cascade_implies_ESS (frac : ℝ) (h : cascades frac) :
44 isESS frac := h
45
46/-- Below threshold does not cascade. -/
47theorem subcritical_does_not_cascade (frac : ℝ) (h : frac < cascadeThreshold) :
48 ¬ cascades frac := by
49 unfold cascades
50 push_neg
51 exact h
52
53/-- Full cooperation cascades. -/
54theorem full_cooperation_cascades : cascades 1 := by
55 unfold cascades cascadeThreshold cooperatorThreshold
56 have hphi : 1 < phi := by have := phi_gt_onePointFive; linarith
57 rw [div_le_iff₀ phi_pos]
58 linarith
59
60/-! ## Master certificate -/
61
62/-- **COOPERATION CASCADE MASTER CERTIFICATE.** -/
63structure CooperationCascadeCert where
64 threshold_eq : cascadeThreshold = 1 / phi
65 cascade_implies_ess : ∀ frac : ℝ, cascades frac → isESS frac
66 full_cooperation : cascades 1
67
68/-- The master certificate is inhabited. -/
69def cooperationCascadeCert : CooperationCascadeCert where
70 threshold_eq := rfl
71 cascade_implies_ess := cascade_implies_ESS
72 full_cooperation := full_cooperation_cascades
73