English
Every module is canonically oriented when the index set is empty.
Русский
Каждый модуль имеет каноническую ориентацию при пустом индексе.
LaTeX
$$$\text{IsEmpty.oriented}: \text{instance oriented for IsEmpty ι}$$$
Lean4
/-- A module is canonically oriented with respect to an empty index type. -/
instance (priority := 100) oriented [IsEmpty ι] : Module.Oriented R M ι where
positiveOrientation :=
rayOfNeZero R (AlternatingMap.constLinearEquivOfIsEmpty 1) <|
AlternatingMap.constLinearEquivOfIsEmpty.injective.ne (by exact one_ne_zero)