Theorem bicom1

Description: Commutative law for the biconditional. (Contributed by Wolf Lammen, 10-Nov-2012)

	Ref	Expression
Assertion	bicom1	|- ( ( ph <-> ps ) -> ( ps <-> ph ) )

Proof

Step	Hyp	Ref	Expression
1		biimpr	|- ( ( ph <-> ps ) -> ( ps -> ph ) )
2		biimp	|- ( ( ph <-> ps ) -> ( ph -> ps ) )
3	1 2	impbid	|- ( ( ph <-> ps ) -> ( ps <-> ph ) )