English
Let F ⊆ E be a field extension. Then the intersection of the separable closure of F in E with the perfect closure of F in E is as small as possible (the base field).
Русский
Пусть F ⊆ E — растяжение полей. Тогда пересечение разделимого замыкания F в E и идеального замыкания F в E равно нижнему элементу (базовому полю).
LaTeX
$$$\mathrm{separableClosure}(F,E) \cap \mathrm{perfectClosure}(F,E) = \bot$$$
Lean4
theorem separableClosure_inf_perfectClosure : separableClosure F E ⊓ perfectClosure F E = ⊥ :=
haveI := (le_separableClosure_iff F E _).mp (inf_le_left (b := perfectClosure F E))
haveI := (le_perfectClosure_iff F E _).mp (inf_le_right (a := separableClosure F E))
eq_bot_of_isPurelyInseparable_of_isSeparable _