Metamath Proof Explorer


Theorem ofmresex

Description: Existence of a restriction of the function operation map. (Contributed by NM, 20-Oct-2014)

Ref Expression
Hypotheses ofmresex.a ⊢ φ → A ∈ V
ofmresex.b ⊢ φ → B ∈ W
Assertion ofmresex ⊢ φ → ∘ f ⁡ R ↾ A × B ∈ V

Proof

Step Hyp Ref Expression
1 ofmresex.a ⊢ φ → A ∈ V
2 ofmresex.b ⊢ φ → B ∈ W
3 1 2 xpexd ⊢ φ → A × B ∈ V
4 ofexg ⊢ A × B ∈ V → ∘ f ⁡ R ↾ A × B ∈ V
5 3 4 syl ⊢ φ → ∘ f ⁡ R ↾ A × B ∈ V