Theorem nelne2 2427

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 2229	. . . 4 |- ( A = B -> ( A e. C <-> B e. C ) )
2	1	biimpcd 158	. . 3 |- ( A e. C -> ( A = B -> B e. C ) )
3	2	necon3bd 2379	. 2 |- ( A e. C -> ( -. B e. C -> A =/= B ) )
4	3	imp 123	1 |- ( ( A e. C /\ -. B e. C ) -> A =/= B )

Syntax hints:   -. wn 3   -> wi 4   /\ wa 103   = wceq 1343   e. wcel 2136   =/= 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  ax-5 1435  ax-gen 1437  ax-ie1 1481  ax-ie2 1482  ax-4 1498  ax-17 1514  ax-ial 1522  ax-ext 2147

This theorem depends on definitions:  df-bi 116  df-cleq 2158  df-clel 2161  df-ne 2337

This theorem is referenced by:  nelelne  2428  elnelne2  2441  zgt1rpn0n1  9631