Theorem ibdr

Description: Reverse of ibd . (Contributed by Rodolfo Medina, 30-Sep-2010)

	Ref	Expression
Hypothesis	ibdr.1	|- ( ph -> ( ch -> ( ps <-> ch ) ) )
Assertion	ibdr	|- ( ph -> ( ch -> ps ) )

Proof

Step	Hyp	Ref	Expression
1		ibdr.1	|- ( ph -> ( ch -> ( ps <-> ch ) ) )
2	1	bicomdd	|- ( ph -> ( ch -> ( ch <-> ps ) ) )
3	2	ibd	|- ( ph -> ( ch -> ps ) )