English
The lexicographic bottom of a sum is the bottom of the left component.
Русский
Лексикографическая нулевая нижняя граница суммы равна нулю слева.
LaTeX
$$$\\text{OrderBot}(\\alpha \\oplus_ℓ \\beta)$ with bottom = inl ⊥$$
Lean4
/-- The lexicographical bottom of a sum is the bottom of the left component. -/
instance orderBot [LE α] [OrderBot α] [LE β] : OrderBot (α ⊕ₗ β)
where
bot := inl ⊥
bot_le := by
rintro (a | b)
· exact Lex.inl bot_le
· exact Lex.sep _ _