Theorem necon3d 2379

Description: Contrapositive law deduction for inequality. (Contributed by NM, 10-Jun-2006.)

Hypothesis

Ref	Expression
necon3d.1	|- ( ph -> ( A = B -> C = D ) )

Assertion

Ref	Expression
necon3d	|- ( ph -> ( C =/= D -> A =/= B ) )

Proof of Theorem necon3d

Step	Hyp	Ref	Expression
1		necon3d.1	. . 3 |- ( ph -> ( A = B -> C = D ) )
2	1	necon3ad 2377	. 2 |- ( ph -> ( C =/= D -> -. A = B ) )
3		df-ne 2336	. 2 |- ( A =/= B <-> -. A = B )
4	2, 3	syl6ibr 161	1 |- ( ph -> ( C =/= D -> A =/= B ) )

Syntax hints:   -. wn 3   -> wi 4   = wceq 1343   =/= wne 2335

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 2336

This theorem is referenced by:  necon3i  2383  pm13.18  2416  ssn0  3450  suppssfv  6045  suppssov1  6046  nnmord  6481  findcard2  6851  findcard2s  6852  addn0nid  8268  nn0n0n1ge2  9257  xnegdi  9800  efne0  11615  divgcdcoprmex  12030  pceulem  12222  pcqmul  12231  pcqcl  12234  pcaddlem  12266  pcadd  12267