Theorem nelne2 2503

Description: Two classes are different if they don't belong to the same class. (Contributed by NM, 25-Jun-2012.)

Assertion

Ref	Expression
nelne2	|- ( ( A e. C /\ -. B e. C ) -> A =/= B )

Proof of Theorem nelne2

Step	Hyp	Ref	Expression
1		eleq1 2295	. . . 4 |- ( A = B -> ( A e. C <-> B e. C ) )
2	1	biimpcd 159	. . 3 |- ( A e. C -> ( A = B -> B e. C ) )
3	2	necon3bd 2455	. 2 |- ( A e. C -> ( -. B e. C -> A =/= B ) )
4	3	imp 124	1 |- ( ( A e. C /\ -. B e. C ) -> A =/= B )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 104   = wceq 1398   e. wcel 2203   =/= wne 2412

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  ax-5 1496  ax-gen 1498  ax-ie1 1542  ax-ie2 1543  ax-4 1559  ax-17 1575  ax-ial 1583  ax-ext 2214

This theorem depends on definitions:  df-bi 117  df-cleq 2225  df-clel 2228  df-ne 2413

This theorem is referenced by:  nelelne  2504  elnelne2  2517  zgt1rpn0n1  10028  cats1un  11413