Theorem necom

Description: Commutation of inequality. (Contributed by NM, 14-May-1999)

	Ref	Expression
Assertion	necom	|- ( A =/= B <-> B =/= A )

Proof

Step	Hyp	Ref	Expression
1		eqcom	|- ( A = B <-> B = A )
2	1	necon3bii	|- ( A =/= B <-> B =/= A )