English
For a < b, a function f is continuous at b on the half-open interval Ioc(a,b) if and only if it is continuous at b on the left-closed ray Iic(b).
Русский
Для a < b функция f непрерывна в точке b на полуоткрытом интервале Ioc(a,b) тогда и только тогда, когда она непрерывна слева на луче Iic(b).
LaTeX
$$$ a < b \rightarrow (ContinuousWithinAt f (Ioc a b) b \leftrightarrow ContinuousWithinAt f (Iic b) b) $$$
Lean4
@[simp]
theorem continuousWithinAt_Ioc_iff_Iic (h : a < b) :
ContinuousWithinAt f (Ioc a b) b ↔ ContinuousWithinAt f (Iic b) b := by
simp only [ContinuousWithinAt, nhdsWithin_Ioc_eq_nhdsLE h]