English
A bounded generalized Boolean algebra is a Boolean algebra.
Русский
Если обобщённая булева алгебра ограничена сверху и снизу, она является булевой алгеброй.
LaTeX
$$$\\alpha \\text{ bounded generalized Boolean algebra } \\Rightarrow \\text{Boolean algebra }(\\alpha)$$$
Lean4
/-- A bounded generalized Boolean algebra is a Boolean algebra. -/
abbrev toBooleanAlgebra [GeneralizedBooleanAlgebra α] [OrderTop α] : BooleanAlgebra α
where
__ := ‹GeneralizedBooleanAlgebra α›
__ := GeneralizedBooleanAlgebra.toOrderBot
__ := ‹OrderTop α›
compl a := ⊤ \ a
inf_compl_le_bot _ := disjoint_sdiff_self_right.le_bot
top_le_sup_compl _ := le_sup_sdiff
sdiff_eq a
b := by
change _ = a ⊓ (⊤ \ b)
rw [← inf_sdiff_assoc, inf_top_eq]