English
For a constant b and a filter f on α that is nontrivial, the liminf of the constant function equal to b is b.
Русский
Для константы b и фильтра f на α, не равного нижней границе, liminf константной функции равен b.
LaTeX
$$$ \\operatorname{liminf} (\\lambda x. b) \\, f = b $$$
Lean4
@[simp]
theorem liminf_const {α : Type*} [ConditionallyCompleteLattice β] {f : Filter α} [NeBot f] (b : β) :
liminf (fun _ => b) f = b :=
limsup_const (β := βᵒᵈ) b