Remove maximal chain witness from FiniteHeightLattice

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lean/Spa/Lattice/AboveBelow.lean

@@ -234,10 +234,7 @@ instance [Inhabited α] : FiniteHeightLattice (AboveBelow α) where
   toLattice := inferInstance
   toOrderBot := inferInstance
   toOrderTop := inferInstance
-  longestChain :=
-    ((RelSeries.singleton _ bot).snoc (mk default)
-        (by rw [RelSeries.last_singleton]; exact bot_lt_mk default)).snoc top
-      (by rw [RelSeries.last_snoc]; exact mk_lt_top default)
+  height := 2
   chains_bounded := boundedChains
 
 end AboveBelow

lean/Spa/Lattice/Bool.lean

@@ -31,8 +31,7 @@ instance : FiniteHeightLattice Bool where
   toLattice := inferInstance
   toOrderBot := inferInstance
   toOrderTop := inferInstance
-  longestChain := (RelSeries.singleton _ (⊥ : Bool)).snoc (⊤ : Bool)
-    (by rw [RelSeries.last_singleton]; exact bot_lt_top)
+  height := 1
   chains_bounded := boundedChains
 
 end Bool

lean/Spa/Lattice/Tuple.lean

@@ -107,66 +107,18 @@ section FiniteHeight
 
 variable [FiniteHeightLattice β]
 
-private lemma consBot_strictMono {n : ℕ} :
-    StrictMono (fun b : β => (Fin.cons b (⊥ : Fin n → β) : Fin (n + 1) → β)) := by
-  intro a b hab
-  refine lt_iff_le_and_ne.mpr ⟨?_, ?_⟩
-  · refine Pi.le_def.mpr (fun i => Fin.cases ?_ (fun j => ?_) i)
-    · simpa using hab.le
-    · simp
-  · exact fun h => hab.ne (by simpa using congrFun h 0)
-
-private lemma consTop_strictMono {n : ℕ} :
-    StrictMono (fun f : Fin n → β => (Fin.cons (⊤ : β) f : Fin (n + 1) → β)) := by
-  intro f g hfg
-  refine lt_iff_le_and_ne.mpr ⟨?_, ?_⟩
-  · refine Pi.le_def.mpr (fun i => Fin.cases ?_ (fun j => ?_) i)
-    · simp
-    · simpa using Pi.le_def.mp hfg.le j
-  · intro h
-    apply hfg.ne
-    funext j
-    simpa using congrFun h j.succ
-
-/-- The maximal chain in `Fin n → β`: walk the first tuple element from `⊥` to `⊤`
-    through `β`'s longest chain, then do that with the second element, and so on. -/
-private def stdChain : (n : ℕ) →
-    { s : LTSeries (Fin n → β) //
-        s.head = (⊥ : Fin n → β) ∧
-        s.length = n * (FiniteHeightLattice.longestChain (α := β)).length }
-  | 0 => ⟨RelSeries.singleton _ ⊥, by rw [RelSeries.head_singleton], by simp⟩
-  | n + 1 =>
-      let prev := stdChain n
-      ⟨RelSeries.smash
-          ((FiniteHeightLattice.longestChain (α := β)).map
-            (fun b => (Fin.cons b (⊥ : Fin n → β) : Fin (n + 1) → β)) consBot_strictMono)
-          (prev.1.map (fun f => (Fin.cons (⊤ : β) f : Fin (n + 1) → β)) consTop_strictMono)
-          (by
-            rw [LTSeries.last_map, LTSeries.head_map,
-              FiniteHeightLattice.longestChain_last, prev.2.1]),
-        by
-          simp only [RelSeries.head_smash, LTSeries.head_map]
-          rw [FiniteHeightLattice.longestChain_head]
-          funext i
-          refine Fin.cases ?_ (fun j => ?_) i <;> simp [Pi.bot_apply],
-        by
-          show (FiniteHeightLattice.longestChain (α := β)).length + prev.1.length
-              = (n + 1) * (FiniteHeightLattice.longestChain (α := β)).length
-          rw [prev.2.2, Nat.succ_mul]; exact Nat.add_comm _ _⟩
-
 instance instFiniteHeight {n : ℕ} : FiniteHeightLattice (Fin n → β) where
   toLattice := inferInstance
   toOrderBot := inferInstance
   toOrderTop := inferInstance
-  longestChain := (stdChain n).1
+  height := n * FiniteHeightLattice.height (α := β)
   chains_bounded := fun c => by
     obtain ⟨cs, _, _, hbound⟩ := exists_unzip c
     refine hbound.trans ?_
-    rw [(stdChain n).2.2]
     calc ∑ i, (cs i).length
-        ≤ ∑ _i : Fin n, (FiniteHeightLattice.longestChain (α := β)).length :=
+        ≤ ∑ _i : Fin n, FiniteHeightLattice.height (α := β) :=
           Finset.sum_le_sum (fun i _ => FiniteHeightLattice.chains_bounded (cs i))
-      _ = n * (FiniteHeightLattice.longestChain (α := β)).length := by
+      _ = n * FiniteHeightLattice.height (α := β) := by
           simp [Finset.sum_const, Finset.card_univ, Fintype.card_fin]
 
 end FiniteHeight