fix: update named argument b₁ → a₁ for GaloisConnection.u_inf

The `@[to_dual]` attribute generates `u_inf` from `l_sup`, which uses
`a₁`/`a₂` as parameter names instead of the old `b₁`/`b₂`.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: kim-em

Mathlib/Algebra/Module/Torsion/Basic.lean

@@ -427,7 +427,7 @@ theorem supIndep_torsionBySet_ideal (hp : (S : Set ι).Pairwise fun i j => p i 
   rw [disjoint_iff, Finset.sup_eq_iSup,
     iSup_torsionBySet_ideal_eq_torsionBySet_iInf fun i hi j hj ij => hp (hT hi) (hT hj) ij]
   have := GaloisConnection.u_inf
-    (b₁ := OrderDual.toDual (p i)) (b₂ := OrderDual.toDual (⨅ i ∈ T, p i)) (torsion_gc R M)
+    (a₁ := OrderDual.toDual (p i)) (a₂ := OrderDual.toDual (⨅ i ∈ T, p i)) (torsion_gc R M)
   dsimp at this ⊢
   rw [← this, Ideal.sup_iInf_eq_top, top_coe, torsionBySet_univ]
   intro j hj; apply hp hi (hT hj); rintro rfl; exact hiT hj

Mathlib/Topology/Order.lean

@@ -668,10 +668,10 @@ theorem nhds_sInf {s : Set (TopologicalSpace α)} {a : α} :
     @nhds α (sInf s) a = ⨅ t ∈ s, @nhds α t a :=
   (gc_nhds a).u_sInf
 
--- Porting note: type error without `b₁ := t₁`
+-- Porting note: type error without `a₁ := t₁`
 theorem nhds_inf {t₁ t₂ : TopologicalSpace α} {a : α} :
     @nhds α (t₁ ⊓ t₂) a = @nhds α t₁ a ⊓ @nhds α t₂ a :=
-  (gc_nhds a).u_inf (b₁ := t₁)
+  (gc_nhds a).u_inf (a₁ := t₁)
 
 theorem nhds_top {a : α} : @nhds α ⊤ a = ⊤ :=
   (gc_nhds a).u_top