153def ChainInfClosed (P : Set (Setoid C)) : Prop :=
proof body
Definition body.
154 ∀ (chain : Set (Setoid C)), chain ⊆ P → chain.Nonempty → IsChain (· ≤ ·) chain → 155 sInf chain ∈ P 156 157/-- **Theorem (Zorn for Recognizers)**: Let P be a nonempty family of setoids 158 on C that is closed under chain infima. Then P contains a minimal element— 159 a finest recognizer-induced equivalence relation. 160 161 Formally: ∃ m ∈ P such that no s ∈ P is strictly finer than m. 162 163 This is the dual of Zorn's Lemma (existence of minimal elements): 164 every chain has a lower bound (the infimum) ⟹ minimal element exists. -/
depends on (14)
Lean names referenced from this declaration's body.