English
For every δ ∈ ℝ, every E ⊆ α, and every x ∈ α, thickenedIndicatorAux δ E x is finite; in particular it is less than ∞.
Русский
Для любых δ ∈ ℝ, любого множества E ⊆ α и любой точки x ∈ α значение thickenedIndicatorAux δ E x конечно и меньше чем ∞.
LaTeX
$$$\forall \delta \in \mathbb{R},\; E \subseteq \alpha,\; x \in \alpha:\; thickenedIndicatorAux(\delta,E)(x) < \infty$$$
Lean4
@[aesop safe (rule_sets := [finiteness])]
theorem thickenedIndicatorAux_lt_top {δ : ℝ} {E : Set α} {x : α} : thickenedIndicatorAux δ E x < ∞ :=
lt_of_le_of_lt (thickenedIndicatorAux_le_one _ _ _) one_lt_top