English
Let a ≤ b. The set of lower bounds of the closed interval [a,b] is the ray (-∞, a], i.e., lowerBounds([a,b]) = Iic(a).
Русский
Пусть a ≤ b. Множество нижних границ замкнутого промежутка [a,b] равно лучу (-∞, a], то есть lowerBounds(Icc(a,b)) = Iic(a).
LaTeX
$$$a \le b \implies \operatorname{lowerBounds}(\\mathrm{Icc}(a,b)) = \\mathrm{Iic}(a).$$$
Lean4
theorem lowerBounds_Icc (h : a ≤ b) : lowerBounds (Icc a b) = Iic a :=
(isGLB_Icc h).lowerBounds_eq