English
The function smoothTransition is monotone on ℝ.
Русский
Функция smoothTransition монотонна на ℝ.
LaTeX
$$$$ \operatorname{Monotone}(\operatorname{smoothTransition}). $$$$
Lean4
protected theorem monotone : Monotone smoothTransition :=
by
intro x y hxy
simp only [smoothTransition]
rw [div_le_div_iff₀ (pos_denom x) (pos_denom y)]
simp only [mul_add, mul_comm (expNegInvGlue x) (expNegInvGlue y), add_le_add_iff_left]
gcongr
· exact expNegInvGlue.nonneg _
· exact expNegInvGlue.nonneg _
· apply expNegInvGlue.monotone hxy
· apply expNegInvGlue.monotone (by linarith)