Theorem sbcel1gv 3105

Description: Class substitution into a membership relation. (Contributed by NM, 17-Nov-2006.) (Proof shortened by Andrew Salmon, 29-Jun-2011.)

Assertion

Ref	Expression
sbcel1gv	|- (A e. V -> ( [.A / x ].x e. B <-> A e. B))

Distinct variable group:   x,B

Allowed substitution hints:   A(x)   V(x)

Proof of Theorem sbcel1gv

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		dfsbcq2 3049	. 2 |- (y = A -> ([y / x]x e. B <-> [.A / x ].x e. B))
2		eleq1 2413	. 2 |- (y = A -> (y e. B <-> A e. B))
3		clelsb3 2455	. 2 |- ([y / x]x e. B <-> y e. B)
4	1, 2, 3	vtoclbg 2915	1 |- (A e. V -> ( [.A / x ].x e. B <-> A e. B))

Syntax hints:   -> wi 4   <-> wb 176  [wsb 1648   e. wcel 1710   [.wsbc 3046

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  df-sbc 3047

This theorem is referenced by: (None)