Theorem ibd

Description: Deduction that converts a biconditional implied by one of its arguments, into an implication. Deduction associated with ibi . (Contributed by NM, 26-Jun-2004)

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

Proof

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