Theorem elab3g 2991

Description: Membership in a class abstraction, with a weaker antecedent than elabg 2986. (Contributed by NM, 29-Aug-2006.)

Hypothesis

Ref	Expression
elab3g.1	⊢ (x = A → (φ ↔ ψ))

Assertion

Ref	Expression
elab3g	⊢ ((ψ → A ∈ B) → (A ∈ {x ∣ φ} ↔ ψ))

Distinct variable groups:   ψ,x   x,A

Allowed substitution hints:   φ(x)   B(x)

Proof of Theorem elab3g

Step	Hyp	Ref	Expression
1		nfcv 2489	. 2 ⊢ ℲxA
2		nfv 1619	. 2 ⊢ Ⅎxψ
3		elab3g.1	. 2 ⊢ (x = A → (φ ↔ ψ))
4	1, 2, 3	elab3gf 2990	1 ⊢ ((ψ → A ∈ B) → (A ∈ {x ∣ φ} ↔ ψ))

Syntax hints:   → wi 4   ↔ wb 176   = wceq 1642   ∈ wcel 1710  {cab 2339

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-v 2861

This theorem is referenced by:  elab3  2992