Theorem nfrexOLD 2921

Description: Obsolete proof of nfrex 2920 as of 30-Dec-2019. (Contributed by NM, 1-Sep-1999.) (Revised by Mario Carneiro, 7-Oct-2016.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypotheses

Ref	Expression
nfrex.1
nfrex.2

Assertion

Ref	Expression
nfrexOLD

Proof of Theorem nfrexOLD

Step	Hyp	Ref	Expression
1		dfrex2 2908	. 2
2		nfrex.1	. . . 4
3		nfrex.2	. . . . 5
4	3	nfn 1901	. . . 4
5	2, 4	nfral 2843	. . 3
6	5	nfn 1901	. 2
7	1, 6	nfxfr 1645	1

Syntax hints:  -.wn 3  F/wnf 1616  F/_wnfc 2605  A.wral 2807  E.wrex 2808

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-10 1837  ax-11 1842  ax-12 1854  ax-13 1999  ax-ext 2435

This theorem depends on definitions:  df-bi 185  df-an 371  df-tru 1398  df-ex 1613  df-nf 1617  df-cleq 2449  df-clel 2452  df-nfc 2607  df-ral 2812  df-rex 2813