Theorem nemtbir 2491

Description: An inference from an inequality, related to modus tollens. (Contributed by NM, 13-Apr-2007.)

Hypotheses

Ref	Expression
nemtbir.1	|- A =/= B
nemtbir.2	|- ( ph <-> A = B )

Assertion

Ref	Expression
nemtbir	|- -. ph

Proof of Theorem nemtbir

Step	Hyp	Ref	Expression
1		nemtbir.1	. . 3 |- A =/= B
2		df-ne 2403	. . 3 |- ( A =/= B <-> -. A = B )
3	1, 2	mpbi 145	. 2 |- -. A = B
4		nemtbir.2	. 2 |- ( ph <-> A = B )
5	3, 4	mtbir 677	1 |- -. ph

Syntax hints:   -. wn 3   <-> wb 105   = wceq 1397   =/= wne 2402

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-in1 619  ax-in2 620

This theorem depends on definitions:  df-bi 117  df-ne 2403

This theorem is referenced by:  opthprc  4777  php5  7043  snnen2oprc  7045  djulclb  7253  ismkvnex  7353  sucpw1nel3  7450  m1exp1  12461  pwle2  16599