Theorem nf3anOLD 2239

Description: Obsolete proof of nf3an 1831 as of 6-Oct-2021. (Contributed by Mario Carneiro, 11-Aug-2016.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypotheses

Ref	Expression
nfanOLDOLD.1	|- F/ x ph
nfanOLDOLD.2	|- F/ x ps
nfanOLD.3	|- F/ x ch

Assertion

Ref	Expression
nf3anOLD	|- F/ x ( ph /\ ps /\ ch )

Proof of Theorem nf3anOLD

Step	Hyp	Ref	Expression
1		df-3an 1039	. 2 |- ( ( ph /\ ps /\ ch ) <-> ( ( ph /\ ps ) /\ ch ) )
2		nfanOLDOLD.1	. . . 4 |- F/ x ph
3		nfanOLDOLD.2	. . . 4 |- F/ x ps
4	2, 3	nfanOLDOLD 2237	. . 3 |- F/ x ( ph /\ ps )
5		nfanOLD.3	. . 3 |- F/ x ch
6	4, 5	nfanOLDOLD 2237	. 2 |- F/ x ( ( ph /\ ps ) /\ ch )
7	1, 6	nfxfrOLD 1837	1 |- F/ x ( ph /\ ps /\ ch )

Syntax hints:   /\ wa 384   /\ w3a 1037   F/wnfOLD 1709

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-12 2047

This theorem depends on definitions:  df-bi 197  df-an 386  df-3an 1039  df-ex 1705  df-nfOLD 1721

This theorem is referenced by:  hb3anOLD  2241