Theorem nfnfOLD 1846

Description: Obsolete proof of nfnf 1845 as of 30-Dec-2017. (Contributed by Mario Carneiro, 11-Aug-2016.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
nfal.1	|- F/xph

Assertion

Ref	Expression
nfnfOLD	|- F/x F/yph

Proof of Theorem nfnfOLD

Step	Hyp	Ref	Expression
1		df-nf 1545	. 2 |- ( F/yph <-> A.y(ph -> A.yph))
2		nfal.1	. . . . . 6 |- F/xph
3	2	a1i 10	. . . . 5 |- ( T. -> F/xph)
4	2	nfal 1842	. . . . . 6 |- F/xA.yph
5	4	a1i 10	. . . . 5 |- ( T. -> F/xA.yph)
6	3, 5	nfimd 1808	. . . 4 |- ( T. -> F/x(ph -> A.yph))
7	6	trud 1323	. . 3 |- F/x(ph -> A.yph)
8	7	nfal 1842	. 2 |- F/xA.y(ph -> A.yph)
9	1, 8	nfxfr 1570	1 |- F/x F/yph

Syntax hints:   -> wi 4   T. wtru 1316  A.wal 1540   F/wnf 1544

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

This theorem depends on definitions:  df-bi 177  df-tru 1319  df-ex 1542  df-nf 1545

This theorem is referenced by: (None)