Metamath Proof Explorer


Theorem bnj1095

Description: First-order logic and set theory. (Contributed by Jonathan Ben-Naim, 3-Jun-2011) (New usage is discouraged.)

Ref Expression
Hypothesis bnj1095.1 ⊢ φ ↔ ∀ x ∈ A ψ
Assertion bnj1095 ⊢ φ → ∀ x φ

Proof

Step Hyp Ref Expression
1 bnj1095.1 ⊢ φ ↔ ∀ x ∈ A ψ
2 hbra1 ⊢ ∀ x ∈ A ψ → ∀ x ∀ x ∈ A ψ
3 1 2 hbxfrbi ⊢ φ → ∀ x φ