Theorem nannanOLD 1349

Description: Obsolete proof of nannan 1348 as of 7-Mar-2020. (Contributed by Jeff Hoffman, 19-Nov-2007.) (Proof modification is discouraged.) (New usage is discouraged.)

Assertion

Ref	Expression
nannanOLD

Proof of Theorem nannanOLD

Step	Hyp	Ref	Expression
1		df-nan 1344	. . 3
2		df-nan 1344	. . . 4
3	2	anbi2i 694	. . 3
4	1, 3	xchbinx 310	. 2
5		iman 424	. 2
6	4, 5	bitr4i 252	1

Syntax hints:  -.wn 3  ->wi 4  <->wb 184  /\wa 369  -/\wnan 1343

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 185  df-an 371  df-nan 1344