Theorem necon3biOLD 2687

Description: Obsolete proof of necon3bi 2686 as of 22-Nov-2019. (Contributed by NM, 1-Jun-2007.) (Proof shortened by Andrew Salmon, 25-May-2011.) (Proof modification is discouraged.) (New usage is discouraged.)

Hypothesis

Ref	Expression
necon3bi.1

Assertion

Ref	Expression
necon3biOLD

Proof of Theorem necon3biOLD

Step	Hyp	Ref	Expression
1		nne 2658	. . 3
2		necon3bi.1	. . 3
3	1, 2	sylbi 195	. 2
4	3	con1i 129	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