Theorem sbc6 3073

Description: An equivalence for class substitution. (Contributed by NM, 23-Aug-1993.) (Proof shortened by Eric Schmidt, 17-Jan-2007.)

Hypothesis

Ref	Expression
sbc6.1	⊢ A ∈ V

Assertion

Ref	Expression
sbc6	⊢ ([̣A / x]̣φ ↔ ∀x(x = A → φ))

Distinct variable group:   x,A

Allowed substitution hint:   φ(x)

Proof of Theorem sbc6

Step	Hyp	Ref	Expression
1		sbc6.1	. 2 ⊢ A ∈ V
2		sbc6g 3072	. 2 ⊢ (A ∈ V → ([̣A / x]̣φ ↔ ∀x(x = A → φ)))
3	1, 2	ax-mp 5	1 ⊢ ([̣A / x]̣φ ↔ ∀x(x = A → φ))

Syntax hints:   → wi 4   ↔ wb 176  ∀wal 1540   = wceq 1642   ∈ wcel 1710  Vcvv 2860  [̣wsbc 3047

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 2479  df-v 2862  df-sbc 3048

This theorem is referenced by:  intab  3957