∀ {α : Type u} {cmp : α → α → Ordering} {β : Type v} {t₁ t₂ : Std.DTreeMap α (fun x => β) cmp} [Std.TransCmp cmp]
  {he : t₁.isEmpty = false} (h : t₁.Equiv t₂), Std.DTreeMap.Const.minEntry t₁ he = Std.DTreeMap.Const.minEntry t₂ ⋯