Theorem necon4aiOLD 2696

Description: Obsolete proof of necon4ai 2695 as of 22-Nov-2019. (Contributed by NM, 16-Jan-2007.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
necon4ai.1

Assertion

Ref	Expression
necon4aiOLD

Proof of Theorem necon4aiOLD

Step	Hyp	Ref	Expression
1		necon4ai.1	. . 3
2	1	con2i 120	. 2
3		nne 2658	. 2
4	2, 3	sylib 196	1

Syntax hints:  -.wn 3  ->wi 4  =wceq 1395  =/=wne 2652

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-ne 2654