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Metamath Proof Explorer

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	$⊢ (φ \to ψ) \to (φ \to ψ)$

Proof

Step	Hyp	Ref	Expression
1		df-vd1	$⊢ (φ \to ψ) \leftrightarrow (φ \to ψ)$
2	1	biimpi	$⊢ (φ \to ψ) \to (φ \to ψ)$