Theorem necon2adOLD 2671

Description: Obsolete proof of necon2ad 2670 as of 23-Nov-2019. (Contributed by NM, 19-Apr-2007.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
necon2ad.1

Assertion

Ref	Expression
necon2adOLD

Proof of Theorem necon2adOLD

Step	Hyp	Ref	Expression
1		nne 2658	. . 3
2		necon2ad.1	. . 3
3	1, 2	syl5bi 217	. 2
4	3	con4d 105	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