Theorem neeq12i 2222

Description: Inference for inequality. (Contributed by NM, 24-Jul-2012.)

Hypotheses

Ref	Expression
neeq1i.1	|- A = B
neeq12i.2	|- C = D

Assertion

Ref	Expression
neeq12i	|- ( A =/= C <-> B =/= D )

Proof of Theorem neeq12i

Step	Hyp	Ref	Expression
1		neeq12i.2	. . 3 |- C = D
2	1	neeq2i 2221	. 2 |- ( A =/= C <-> A =/= D )
3		neeq1i.1	. . 3 |- A = B
4	3	neeq1i 2220	. 2 |- ( A =/= D <-> B =/= D )
5	2, 4	bitri 173	1 |- ( A =/= C <-> B =/= D )

Syntax hints:   <-> wb 98   = wceq 1243   =/= wne 2204

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-in1 544  ax-in2 545  ax-5 1336  ax-gen 1338  ax-4 1400  ax-17 1419  ax-ext 2022

This theorem depends on definitions:  df-bi 110  df-cleq 2033  df-ne 2206

This theorem is referenced by:  3netr3g  2239  3netr4g  2240