Theorem nfnel 2469

Description: Bound-variable hypothesis builder for negated membership. (Contributed by David Abernethy, 26-Jun-2011.) (Revised by Mario Carneiro, 7-Oct-2016.)

Hypotheses

Ref	Expression
nfnel.1	|- F/_ x A
nfnel.2	|- F/_ x B

Assertion

Ref	Expression
nfnel	|- F/ x A e/ B

Proof of Theorem nfnel

Step	Hyp	Ref	Expression
1		df-nel 2463	. 2 |- ( A e/ B <-> -. A e. B )
2		nfnel.1	. . . 4 |- F/_ x A
3		nfnel.2	. . . 4 |- F/_ x B
4	2, 3	nfel 2348	. . 3 |- F/ x A e. B
5	4	nfn 1672	. 2 |- F/ x -. A e. B
6	1, 5	nfxfr 1488	1 |- F/ x A e/ B

Syntax hints:   -. wn 3   F/wnf 1474   e. wcel 2167   F/_wnfc 2326   e/ wnel 2462

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 615  ax-in2 616  ax-io 710  ax-5 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-fal 1370  df-nf 1475  df-sb 1777  df-cleq 2189  df-clel 2192  df-nfc 2328  df-nel 2463

This theorem is referenced by: (None)