Theorem neeq1 2258

Description: Equality theorem for inequality. (Contributed by NM, 19-Nov-1994.)

Assertion

Ref	Expression
neeq1	|- ( A = B -> ( A =/= C <-> B =/= C ) )

Proof of Theorem neeq1

Step	Hyp	Ref	Expression
1		eqeq1 2087	. . 3 |- ( A = B -> ( A = C <-> B = C ) )
2	1	notbid 624	. 2 |- ( A = B -> ( -. A = C <-> -. B = C ) )
3		df-ne 2246	. 2 |- ( A =/= C <-> -. A = C )
4		df-ne 2246	. 2 |- ( B =/= C <-> -. B = C )
5	2, 3, 4	3bitr4g 221	1 |- ( A = B -> ( A =/= C <-> B =/= C ) )

Syntax hints:   -. wn 3   -> wi 4   <-> wb 103   = wceq 1284   =/= wne 2245

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 104  ax-ia2 105  ax-ia3 106  ax-in1 576  ax-in2 577  ax-5 1376  ax-gen 1378  ax-4 1440  ax-17 1459  ax-ext 2063

This theorem depends on definitions:  df-bi 115  df-cleq 2074  df-ne 2246

This theorem is referenced by:  neeq1i  2260  neeq1d  2263  nelrdva  2797  0inp0  3940  uzn0  8634  xrnemnf  8853  xrnepnf  8854  ngtmnft  8885  fztpval  9100