Theorem nfnf1 1597

Description: x is not free in F/ x ph. (Contributed by Mario Carneiro, 11-Aug-2016.)

Assertion

Ref	Expression
nfnf1	|- F/ x F/ x ph

Proof of Theorem nfnf1

Step	Hyp	Ref	Expression
1		df-nf 1514	. 2 |- ( F/ x ph <-> A. x ( ph -> A. x ph ) )
2		nfa1 1594	. 2 |- F/ x A. x ( ph -> A. x ph )
3	1, 2	nfxfr 1527	1 |- F/ x F/ x ph

Syntax hints:   -> wi 4   A.wal 1400   F/wnf 1513

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-5 1500  ax-gen 1502  ax-ial 1587

This theorem depends on definitions:  df-bi 117  df-nf 1514

This theorem is referenced by:  nfimd  1638  nfnt  1708  nfald  1813  equs5or  1883  sbcomxyyz  2032  nfsb4t  2074  nfnfc1  2395  nfabdw  2411  sbcnestgf  3199  dfnfc2  3948  bdsepnft  16827  setindft  16905  strcollnft  16924