Theorem csbtt 3149

Description: Substitution doesn't affect a constant B (in which x is not free). (Contributed by Mario Carneiro, 14-Oct-2016.)

Assertion

Ref	Expression
csbtt	|- ((A e. V /\ F/_xB) -> [_A / x]_B = B)

Proof of Theorem csbtt

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		df-csb 3138	. 2 |- [_A / x]_B = {y | [.A / x ].y e. B}
2		nfcr 2482	. . . 4 |- ( F/_xB -> F/x y e. B)
3		sbctt 3109	. . . 4 |- ((A e. V /\ F/x y e. B) -> ( [.A / x ].y e. B <-> y e. B))
4	2, 3	sylan2 460	. . 3 |- ((A e. V /\ F/_xB) -> ( [.A / x ].y e. B <-> y e. B))
5	4	abbi1dv 2470	. 2 |- ((A e. V /\ F/_xB) -> {y | [.A / x ].y e. B} = B)
6	1, 5	syl5eq 2397	1 |- ((A e. V /\ F/_xB) -> [_A / x]_B = B)

Syntax hints:   -> wi 4   <-> wb 176   /\ wa 358   F/wnf 1544   = wceq 1642   e. wcel 1710  {cab 2339   F/_wnfc 2477   [.wsbc 3047  [_csb 3137

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  df-csb 3138

This theorem is referenced by:  csbconstgf  3150  sbnfc2  3197