Theorem in2

Description: The virtual deduction introduction rule of converting the end virtual hypothesis of 2 virtual hypotheses into an antecedent. (Contributed by Alan Sare, 21-Apr-2011) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Hypothesis	in2.1	|- (. ph ,. ps ->. ch ).
Assertion	in2	|- (. ph ->. ( ps -> ch ) ).

Proof

Step	Hyp	Ref	Expression
1		in2.1	|- (. ph ,. ps ->. ch ).
2	1	dfvd2i	|- ( ph -> ( ps -> ch ) )
3	2	dfvd1ir	|- (. ph ->. ( ps -> ch ) ).