English
For any x ∈ ENNReal, (x : EReal).toENNReal = x.
Русский
Для любого x ∈ ENNReal, если рассмотреть x как элемент EReal, то toENNReal возвращает x.
LaTeX
$$$ \operatorname{toENNReal}((x : \mathrm{EReal})) = x $$$
Lean4
@[simp]
theorem toENNReal_coe {x : ℝ≥0∞} : (x : EReal).toENNReal = x :=
by
by_cases h_top : x = ⊤
· rw [h_top, coe_ennreal_top, toENNReal_top]
rwa [toENNReal, if_neg _, toReal_coe_ennreal, ENNReal.ofReal_toReal_eq_iff]
simp [h_top]