English
If f has unit speed on Icc x y and on Icc y z, then f has unit speed on Icc x z.
Русский
Если у f единичная скорость на Icc(x,y) и на Icc(y,z), то на Icc(x,z) тоже единичная скорость.
LaTeX
$$HasUnitSpeedOn f (Icc x y) → HasUnitSpeedOn f (Icc y z) → HasUnitSpeedOn f (Icc x z)$$
Lean4
theorem union {t : Set ℝ} {x : ℝ} (hfs : HasUnitSpeedOn f s) (hft : HasUnitSpeedOn f t) (hs : IsGreatest s x)
(ht : IsLeast t x) : HasUnitSpeedOn f (s ∪ t) :=
HasConstantSpeedOnWith.union hfs hft hs ht