Theorem rexv

Description: An existential quantifier restricted to the universe is unrestricted. (Contributed by NM, 26-Mar-2004)

	Ref	Expression
Assertion	rexv	⊢ ( ∃ 𝑥 ∈ V 𝜑 ↔ ∃ 𝑥 𝜑 )

Proof

Step	Hyp	Ref	Expression
1		df-rex	⊢ ( ∃ 𝑥 ∈ V 𝜑 ↔ ∃ 𝑥 ( 𝑥 ∈ V ∧ 𝜑 ) )
2		vex	⊢ 𝑥 ∈ V
3	2	biantrur	⊢ ( 𝜑 ↔ ( 𝑥 ∈ V ∧ 𝜑 ) )
4	3	exbii	⊢ ( ∃ 𝑥 𝜑 ↔ ∃ 𝑥 ( 𝑥 ∈ V ∧ 𝜑 ) )
5	1 4	bitr4i	⊢ ( ∃ 𝑥 ∈ V 𝜑 ↔ ∃ 𝑥 𝜑 )