Theorem necon3bbii 2373

Description: Deduction from equality to inequality. (Contributed by NM, 13-Apr-2007.)

Hypothesis

Ref	Expression
necon3bbii.1	|- ( ph <-> A = B )

Assertion

Ref	Expression
necon3bbii	|- ( -. ph <-> A =/= B )

Proof of Theorem necon3bbii

Step	Hyp	Ref	Expression
1		necon3bbii.1	. . . 4 |- ( ph <-> A = B )
2	1	bicomi 131	. . 3 |- ( A = B <-> ph )
3	2	necon3abii 2372	. 2 |- ( A =/= B <-> -. ph )
4	3	bicomi 131	1 |- ( -. ph <-> A =/= B )

Syntax hints:   -. wn 3   <-> wb 104   = wceq 1343   =/= wne 2336

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-in1 604  ax-in2 605

This theorem depends on definitions:  df-bi 116  df-ne 2337

This theorem is referenced by:  ef0lem  11601