2026-06-09 18:48:02 -07:00
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import Spa.Lattice
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namespace Spa
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2026-06-25 13:59:08 -05:00
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lemma boundedChains_of_subsingleton (α : Type*) [Preorder α] [Subsingleton α]
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2026-06-09 18:48:02 -07:00
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(n : ℕ) : BoundedChains α n := fun c => by
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by_contra hc
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push_neg at hc
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exact (c.step ⟨0, by omega⟩).ne (Subsingleton.elim _ _)
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2026-06-22 18:33:48 -05:00
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instance : FiniteHeightLattice PUnit where
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2026-06-25 18:42:28 -05:00
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toLattice := inferInstance
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longestChain := RelSeries.singleton _ PUnit.unit
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2026-06-22 18:33:48 -05:00
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chains_bounded := boundedChains_of_subsingleton PUnit 0
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2026-06-09 18:48:02 -07:00
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end Spa
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