Theorem biimtrrdi

Description: A mixed syllogism inference. (Contributed by NM, 18-May-1994)

	Ref	Expression
Hypotheses	biimtrrdi.1	|- ( ph -> ( ch <-> ps ) )
	biimtrrdi.2	|- ( ch -> th )
Assertion	biimtrrdi	|- ( ph -> ( ps -> th ) )

Proof

Step	Hyp	Ref	Expression
1		biimtrrdi.1	|- ( ph -> ( ch <-> ps ) )
2		biimtrrdi.2	|- ( ch -> th )
3	1	biimprd	|- ( ph -> ( ps -> ch ) )
4	3 2	syl6	|- ( ph -> ( ps -> th ) )