English
For a nonempty Finset s and b with a decidable equality, inserting b yields (insert b s).sup' f = f(b) ⊔ s.sup' H f.
Русский
При вставке элемента b в непустое Finset s имеем sup' при вставке: sup' (insert b s) f = f(b) ⊔ sup' s.
LaTeX
$$$ (insert b s).sup' (insert_nonempty _ _) f = f b \;⊔\; s.sup' H f $$$
Lean4
@[simp]
theorem sup'_insert [DecidableEq β] {b : β} : (insert b s).sup' (insert_nonempty _ _) f = f b ⊔ s.sup' H f :=
by
rw [← WithBot.coe_eq_coe]
simp [WithBot.coe_sup]