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NonCollapseCondition
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IndisputableMonolith.RecogGeom.EffectiveManifold on GitHub at line 100.
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97/-- U4: The refinement does not collapse: at every stage, the quotient
98has at least as many classes as the previous stage (monotone cardinality).
99This prevents dimension from dropping. -/
100structure NonCollapseCondition (sys : DirectedRefinement C) : Prop where
101 nontrivial_at_all_stages : ∀ i : ℕ,
102 ∃ c₁ c₂ : C, ¬Indistinguishable (sys.recognizer i) c₁ c₂
103 monotone_separation : ∀ i : ℕ, ∀ c₁ c₂ : C,
104 ¬Indistinguishable (sys.recognizer i) c₁ c₂ →
105 ¬Indistinguishable (sys.recognizer (i + 1)) c₁ c₂
106
107/-- Monotone separation follows from refinement. -/
108theorem monotone_separation_of_refinement (sys : DirectedRefinement C) :
109 ∀ i : ℕ, ∀ c₁ c₂ : C,
110 ¬Indistinguishable (sys.recognizer i) c₁ c₂ →
111 ¬Indistinguishable (sys.recognizer (i + 1)) c₁ c₂ := by
112 intro i c₁ c₂ hne habs
113 exact hne (sys.refines i c₁ c₂ habs)
114
115/-! ## U1: The Effective Manifold Bundle -/
116
117/-- U1: The complete hypothesis bundle for the effective-manifold assumption.
118This packages U2 + U4 (U3 is a consequence when the limit exists). -/
119structure EffectiveManifoldHypotheses (C : Type*) where
120 system : DirectedRefinement C
121 converges : RefinementConverges system
122 nonCollapse : NonCollapseCondition system
123
124/-- U2 + refinement implies U4's monotone separation automatically. -/
125theorem nonCollapse_monotone_automatic (sys : DirectedRefinement C) :
126 ∀ i c₁ c₂,
127 ¬Indistinguishable (sys.recognizer i) c₁ c₂ →
128 ¬Indistinguishable (sys.recognizer (i + 1)) c₁ c₂ :=
129 monotone_separation_of_refinement sys
130