English
If eventually u x ≠ ⊥ implies p x ↔ q x, then blimsup u f p = blimsup u f q.
Русский
Если из некоторой предельной области следует, что p x ↔ q x, тогда blimsup u f p = blimsup u f q.
LaTeX
$$$\\text{blimsup}(u,f,p) = \\text{blimsup}(u,f,q)$$$
Lean4
theorem blimsup_congr' {f : Filter β} {p q : β → Prop} {u : β → α} (h : ∀ᶠ x in f, u x ≠ ⊥ → (p x ↔ q x)) :
blimsup u f p = blimsup u f q := by
simp only [blimsup_eq]
congr with a
refine eventually_congr (h.mono fun b hb => ?_)
rcases eq_or_ne (u b) ⊥ with hu | hu; · simp [hu]
rw [hb hu]