English
If α is a Preorder and IsTrichotomous α (<), then WithTop α is IsTrichotomous for <.
Русский
Если у α есть предпорядок и IsTrichotomous α(<), то WithTop α сохраняет тричотомичность по '<'.
LaTeX
$$$\\text{IsTrichotomous}(\\mathrm{WithTop}\\,\\alpha, <)$$$
Lean4
instance lt [Preorder α] [IsTrichotomous α (· < ·)] : IsTrichotomous (WithTop α) (· < ·) where
trichotomous x y := by cases x <;> cases y <;> simp [trichotomous]