Theorem dfvd1imp

Description: Left-to-right part of definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011) (Proof modification is discouraged.) (New usage is discouraged.)

	Ref	Expression
Assertion	dfvd1imp	⊢ ( (    𝜑    ▶    𝜓    ) → ( 𝜑 → 𝜓 ) )

Proof

Step	Hyp	Ref	Expression
1		df-vd1	⊢ ( (    𝜑    ▶    𝜓    ) ↔ ( 𝜑 → 𝜓 ) )
2	1	biimpi	⊢ ( (    𝜑    ▶    𝜓    ) → ( 𝜑 → 𝜓 ) )