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	⊢ (    𝜑    ,    𝜓    ▶    𝜒    )
Assertion	in2	⊢ (    𝜑    ▶    ( 𝜓 → 𝜒 )    )

Proof

Step	Hyp	Ref	Expression
1		in2.1	⊢ (    𝜑    ,    𝜓    ▶    𝜒    )
2	1	dfvd2i	⊢ ( 𝜑 → ( 𝜓 → 𝜒 ) )
3	2	dfvd1ir	⊢ (    𝜑    ▶    ( 𝜓 → 𝜒 )    )