Metamath Proof Explorer


Theorem cncfrss2

Description: Reverse closure of the continuous function predicate. (Contributed by Mario Carneiro, 25-Aug-2014)

Ref Expression
Assertion cncfrss2 ⊢ F : A ⟶cn B → B ⊆ ℂ

Proof

Step Hyp Ref Expression
1 df-cncf ⊢ ⟶cn = a ∈ 𝒫 ℂ , b ∈ 𝒫 ℂ ⟼ f ∈ b a | ∀ x ∈ a ∀ y ∈ ℝ + ∃ z ∈ ℝ + ∀ w ∈ a x − w < z → f ⁡ x − f ⁡ w < y
2 1 elmpocl2 ⊢ F : A ⟶cn B → B ∈ 𝒫 ℂ
3 2 elpwid ⊢ F : A ⟶cn B → B ⊆ ℂ